They believe they can change a community from working class/immigrant base to millennial/students/new residents. 

Like many American’s, I'm fed up after watching the health care bill get pushed through and our government saying that they had to ignore us because we don't know better, or the AZ immigration law, or prop 8 in California.

Population growth and net immigration. 

Especially in states like California known to ignore federal law (marijuana and immigration are two examples) and they will side in favor or the tenant when something goes wrong. 

Hello BP Family,After contemplating for a few minutes the type of impression I wanted to make with my introduction I simply realize that if this community truly was going to become a part of my family I should be transparent from the start.After immigrating from Mexicali,  Baja California in Northern Mexico I dedicated all of my effort to school which earned me a place at UC Berkeley for my college career.

With immigration this problem should work itself out.Low cost housing should stay in demand, mcmansions, maybe not.What people on this site propose is to buy property that makes sense today and don't expect appreciation to fix negative cash-flow.In any case, some areas can experience vacancy problems.

To make matters worse, this family appeared to be undocumented immigrants and were in a fight with the buyer claiming they paid him rent the month he stopped paying me and so on.

The tenants are all immigrants.  

I have been in bay area for more than 12 years now, immigrated from India.

It's traditionally a fairly poor working class neighbourhood with many immigrants, but in the recent years, more tourists have acquired property here - due to the location mentioned above and an increase in house-flipping happening here.There are many opportunities for making good RE investments in Barcelona, but if you're looking for a cheap "buy and hold" investment, there might be better cities to place your money.