Special repayments or investing in the market? Alternatives?

That is certainly inaccurate in such a general way. If everything goes well (ex-post), it may be okay to let the debt run longer. But that is quite risky over 20 or even 30 years. You don’t get a dividend yield of 7.6% without risk, especially not over 30 years.
This strategy is a bet and not a sure thing. The old-fashioned rule that nothing is better than investing in paying off debt has already survived some ups & downs. As a private individual without much play money, I would approach this very defensively and at least rigorously carry out the necessary high repayment (3%+) for a low-interest period.

By the way, I have been invested in telecommunications since 2008, for example (freenet etc.), and except for 2020 have achieved dividends of 7% and more every year. During this time, I sold several times with high profits and re-entered at low prices.
ETFs run as monthly savings plans and asset-forming benefits on the side. As mentioned, the calculated special repayments also flow into an ETF. The mortgage trickles along quietly like a rent that must never be increased.

If the prices are down, I don't have to trade.

You are highly indebted - so you may possibly be forced to trade. If interest rates rise, the value of your portfolio and, the great danger, the value of your house will plummet. The bank can therefore demand additional collateral, otherwise foreclosure threatens. The forced sale of your assets will probably yield less than if you had repaid normally. It therefore depends greatly - if you already have a healthy amount of equity in the financing and are repaying heavily anyway, the risk is significantly lower than if you pursue minimal equity + minimal repayment as a financing strategy.

You are heavily in debt - so you could possibly be forced to take action. If interest rates rise, the value of your portfolio and, the big risk, that of your house will drop sharply. The bank can therefore demand additional collateral, otherwise a forced auction threatens. The forced sale of your assets will probably yield less than if you had paid off regularly. It therefore depends heavily - if you already have a healthy amount of equity in the financing, and are paying off heavily anyway, the risk is significantly lower than if you pursue minimal equity + minimal repayment as a financing strategy.

I estimate this risk as very low. If the value of our apartment drops sharply, then all properties in this area will also drop sharply in price. Most here have financed either through the blue or red regional bank. If both now call in all loans and aim for an auction, the prices achievable would completely collapse. Therefore, I do not assume this scenario.

Very interesting topic.

We built in 2017, a full repayment loan at 1.83% for 28 years. Equity share was about 40%.

After moving in, I completely took my "retirement provision" into my own hands and restructured it:

- Cancelled the capital-forming life insurance
- Cancelled the home savings contract
- Took all the money and invested 70% in ETFs (70% Vanguard Developed World, 30% Emerging Markets) in several tranches, 30% in a savings account
- Since then, a monthly savings plan has been running. At the end of the year, a rebalancing is done and that’s it.

Inflation-adjusted, my portfolio is currently at about 8% p.a.

This year and last year we used the maximum possible 3% extra repayment. I probably wouldn’t do that anymore and would rather invest in ETFs.

The loan installment amounts to about 22% of net income if my wife ever works again, the remaining debt is now about 40% of the property’s value. Why should I put more into the “house” lump?

If my wife weren’t so security-conscious, we certainly wouldn’t have made extra repayments and invested much more of our savings in stocks.

I should tackle the topic of advance planning again; she is now a bit more risk-tolerant... ;)

I should tackle the topic of advance payment again, advance payment has become a bit more risk-friendly by now... ;)

She doesn’t need to become more risk-friendly at all, but simply reassess for herself and then realize that the risk has meanwhile decreased. From 60% loan-to-value it has become 40% loan-to-value, you have accumulated liquid assets for unforeseen events in the overnight money account and portfolio, a second income would be feasible.

Very interesting topic. We built in 2017, full repayment loan at 1.83% for 28 years. Equity share was about 40%....

That's interesting. You have almost the same numbers as we do. 1.56% for 28 years, as far as I remember. I see it exactly the same way as you. But I wonder why you put 30% into a daily money account. I just googled it and found 0.15% interest p.a. for daily money. That’s no longer an investment, but rather "30% we haven’t invested" ;) I would always leave a certain liquid reserve in the account, but 30% doesn’t sound like a little amount, unless you have invested only 20 or 30k€ in total.