Construction costs are currently skyrocketing

You can also estimate more easily. The buyer has total costs of €750,000 for his house over 30 years and an equity value of €750,000 (assuming: appreciation offsets operating and maintenance costs) The tenant pays an average of €24,000 p.a. x 30 years = €720,000 for a comparable rental property. Considering the different distribution of expenses over the years and the investment of the money not spent - whenever it would be available - the tenant would have to build up €750,000 capital to be "pari" with the buyer after 30 years. If ETFs can do that - all respect! I just don't believe it.

That is on average a rent of €2000 per month from a sporty perspective.

That's an average rent of €2000 per month, quite sporty.

I simply estimated the average warm rent (expenses) of a semi-detached house with today's purchase price of €500,000 in the vicinity of a larger city. Even if you go down by 25%, you still won't make it with the ETFs.

Not as sporty as you think. Just calculate a rent increase of an extremely moderate 1% p.a. - that's amazing, how the rent will be in 30 years.