Your first book already teaches you everything you need to know to start investing in ETFs. Why write a second one?

Starting turned out to be the easy half.

I finished De hangmatbelegger telling myself I would never write another one. I say the same thing in the acknowledgements of this one.

Then the emails and DMs started arriving. They were not from people asking how to begin. They were from people who had already begun, asking whether they were still doing it right. We collected 164 of those questions and built the second book around them.

By then the first book had clearly landed. Van Dale made "hangmatbeleggen" its 2024 Word of the Year in Flanders and gave the word a permanent place in the dictionary. Hangmatbeleggen has become the Dutch word for passive investing. You own a tiny piece of every listed company through broad ETFs, and then make as few decisions as you can. Private banks wrote internal briefings teaching their advisers how to handle clients who had read us. Nobody needed convincing any more that passive investing beats picking funds. What nobody had written down was the part that comes after.

What do readers actually get stuck on?

Almost never the mechanics. It is the behaviour.

Hardly anyone writes to ask which ETF to buy. They ask whether to step out until the war is over, whether to wait for the dip, whether a portfolio down 8% after six months means they picked wrong. Two habits of mind do most of the damage.

The first is outcome bias, which means judging a decision by how it turned out. One reader wrote that his returns were downright disappointing, that he was not even beating the savings rate, and that he would stop if it did not change soon. He sold shortly afterwards. His timing was unlucky. His decision to start was not wrong.

Then there is recency bias. Whatever did well lately starts to look like the future. In 2023 readers asked why our model portfolios were not 100% S&P 500. In 2026 they complained that world ETFs are investing too much in the US.

Together they produce the behaviour gap, which is the return that we lose due to our behavioural biases. Morningstar's Mind the Gap 2025 puts it at 1.2% a year for the average dollar in US funds and ETFs over the ten years to December 2024. The breakdown matters more than the average. Sector funds lost 1.5% a year to it. All-in-one funds, the broad ones that handle the asset allocation for you, lost just 0.1%. The simpler and broader the fund, the more of its return its investors actually keep.

So where should someone start?

With a portfolio spread across the whole world economy, and only money you will not need for years.

Boring is the point rather than a compromise. Two things matter for someone starting out.

The first is the order you do things in. Build an emergency fund, then set aside the goals that are only a few years away, then invest what is left for the long term. The first phase of adult life is the expensive one: a flat, a wedding, children, a renovation that costs more than the quote. The worst thing that can happen to a long-term investor is being forced to sell while the market is down.

The second is to own the whole world instead of the part you recognise. A BEL 20 tracker feels safer to a Belgian because you know the names, but it holds less than 0.3% of the world's listed companies and skips the sectors Belgium barely has, such as software and luxury goods. A world ETF owns all of it. After that, the only real decision left is how much of the portfolio sits in shares and how much in bonds, and that follows from when you need the money and how large a drop you can live through. It is a question about you, not about the market.

How do you get children involved in your investments?

The financial upbringing matters more than the account.

Make money tangible before you make it technical. A child can grasp that a world ETF makes them a very small part-owner of the company that makes their phone, their trainers and their films. If you keep a portfolio for them, look at it together once a year. The aim is not to raise a day trader.

Then the awkward part. Investing in a child's own name is difficult in Belgium. Few platforms offer it. Parents get steered towards defensive or expensive bank and insurance products, where 2% a year in fees quietly eats a large share of eighteen years of growth. A big withdrawal from a minor's account can need sign-off from the justice of the peace, the local judge who guards a child's assets. And on the eighteenth birthday your child gets full access, whether or not that is the right year for it.

So Tim and I both invest on our own name instead, with a separate portfolio per child. Next to my own I keep one for my daughter and one for my nephew. It costs less, and we decide when the money is handed over. Both routes have real trade-offs.

For a young adult, a match works better than a lecture. When they get their first pay cheque, offer to put in whatever they put in, and buy a world ETF with the total. It solves the hardest problem, which is starting.

And near the end: retirement, and passing it on?

Retiring is not the day you sell everything.

The years just before and just after you stop working are the dangerous ones. The book calls that window the fragile decade. A crash at 67, with a full portfolio and withdrawals just starting, does lasting damage, because you are selling into it. The same crash at 85, with the state pension covering the basics, usually does not. The caution belongs around the retirement date, not spread evenly across the rest of your life.

Spending you can see coming needs its own money. If a motorhome and a tour of Europe are the plan for your first year of retirement, that money should be somewhere safe years before you stop working, not in equity ETFs you have to sell into whatever the market is doing that week. Bonds pay less and pay more predictably. That is the trade you are making.

The old rule of thumb says to hold 100 minus your age in shares, so 35% at 65. That rule comes from a time when people died younger and bonds paid more. Somebody who stops working at 65 today may live another thirty years, and a portfolio that defensive will not keep up with inflation over a stretch like that. So think in pots instead of in one number. Split the money by what each part is for: the basics, the first years of extra spending, the pot you are still growing for the long term, and the part your children will probably inherit. That last pot has their horizon, which can easily be thirty or forty years. For that money, your age is a bad guide.

The last piece is the one people skip. In most households one partner is the CFO. They know the logins, the accounts, and why each holding is there. That works until it does not. A portfolio of one or two broad ETFs is easy to explain and easy for somebody else to keep going. What you want to avoid is your family selling everything in a hurry because nobody knows what it was for.

Who is Hangmatbelegger voor het leven for?

Anyone who already owns something and would like to still own it in twenty years, whether or not they read the first book.

The sequel does not assume having read De hangmatbelegger. It assumes a reader with a portfolio and a life happening around it: a partner, a mortgage, children, a career that changes, a retirement date somewhere ahead. If you have not started yet, one of these books will get you going, and the interview we did about the first one covers that half of the story.

I wrote Hangmatbelegger voor het leven with Tim Nijsmans. Lannoo published it in August 2026. Het Laatste Nieuws covered it around five moments in a life when a passive investor has to act, and Robin Boone went through it part by part on his Fintastisch podcast. You can order it at dehangmatbelegger.be.

Staying invested is the decision that pays

Choosing the portfolio is a decision you make once. Keeping it is a decision you make again every year for thirty years, through a crash, a renovation, a baby and a retirement date. The second one is where the money is.

The numbers say the same thing. Investors in broad all-in-one funds gave up 0.1% a year to their own timing, while investors in sector funds gave up 1.5%. A portfolio you barely think about is one you are still holding in year twelve, and that is where the missing 1.4% comes from.

So pick something boring enough that you will still hold it when the news is bad, and make the monthly deposit a thing you never have to decide on again. With Curvo that takes a few minutes to set up. The rest of it, thirty years' worth, is in the book.