system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is it sustainable for house prices to be going up 5, 7, 10% when real income is only increasing 1-3% and real inflation is only 1-2%?

This appears to be a problem worldwide. House prices in Vienna increased almost 10%/year between 2007-2014 even though nominal income (including inflation) rarely increases that fast in anywhere not named China.
gpt
It isn't sustainable.  The rapid inflation of US housing prices and subsequent collapse of the housing market left a lot of over-valued foreclosures on bank books and played a major role in the 2008/9 financial crisis.