Earlier quoted context omitted.
In the United States, people who don't have significant financial support from their parents graduate from university with a great deal of debt.
Indeed. But those are the same people getting those $150k entry-level salaries from companies in the Bay Area. Even after paying down $50k/year in debt one would be hard pressed to spend the rest of that without saving anything. You spend your college years sharing a house with 5 roommates, driving an $800 car and living on Costco pallets of canned chili. Keep that up for another few years after school while pulling…
The reality is, not everyone lives in California. Entry level salaries have certainly increased since I graduated, but they're still not $100k+. Advanced payments are hard to make when you're just getting started and have nothing to stand on.
I'm not arguing that it's not possible, I'm only arguing that your imagination of how much money the average jr developer has to splash is not realistic.