Kann das wahr sein?

Probably.

Looking at older stats, average gross income is apparently in the 80k region. So 4.2K net per month as average salary. The average employee would need to spend in excess of 1.7K to fall into the +40% bracket.

Now, there are plenty of folks that earn far less than 4.2K and spend more than 40% of their income on housing BUT there’s also plenty of folks that have paid of their mortgages and have minimal housing costs (tax, insurance, charges).