I think you're mistaking a small subset for the general set of home owners.
The root cause of what you're talking about is demand is exceeding supply, by quite a long way. The population is growing - through various means - faster than homes are being created. That means a few home owners will do what you describe.
Prop 13 means local municipalities need to extract higher fees and taxes on new construction compared to existing property. Higher development costs/prices cause dead weight loss and therefore block/reduce new development.
The root cause of what you're talking about is demand is exceeding supply, by quite a long way. The population is growing - through various means - faster than homes are being created. That means a few home owners will do what you describe.