If private investment had allowed for people of all income types to live in your neighborhood, then the investment wouldn’t stop. However from your description it sounds like the “private investment” was people similar to you that wanted to create a neighborhood of ONLY private investor housing (wealthy). That’s why Barcelona decided that 50-70% must be available for lower income levels. Otherwise it ends up like America where only 0-20% of housing must be affordable and the market ends up being mostly 2nd homes for the wealthy. Mostly empty buildings, dead neighborhoods, and airbnbs.
There are many people that are willing to rent at the market rate? I would argue that if there is more supply on the market property owners will be forced to rent at lower prices?
For those who do not I would create incentives like raising taxes for empty property.
