“So somehow they are managing $4000 or more payments for these places.”
Remember that $4000 monthly payment includes maybe $1000 going to equity and another $1000 off your income taxes. So are they getting something better than they could rent for $2000? Because that is the effective price they are paying, not $4000.
I made my first purchase in SD at the bottom of the market when I was 30. Did not get family help, had to save the 5% down payment myself. Best financial decision of my life, between rent and tax savings and appreciation, I might be up half a million dollars on it. And I like living there too. I refinanced into “no cost” 20% down loan about 10 months after the purchase. This was easy to do, and would be my suggestion given the difficulty of saving from working 20% of the typical San Diego home.