They're mixed up in political lobbying and fundraising, it's quite possible they are independently and legally if immorally wealthy.

Their son had this crypto exchange that was flinging money in every-which-direction.

Another question, what if they are still paying a mortgage? Then they are “bailing on leverage”? Committing the bank’s home to the US govt.

This isn't super relevant, but academia in the US pays very well. This is even more so the case for law, business, engineering, medicine, and a few other areas.

Obviously not relevant in the context of $250 million.

Law professors make much better money than most academics, with starting salaries more than double what humanities professors make. These are also senior professors who have been at Stanford for a long time, making good money and presumably investing along the way. SBF's dad is a famous tax law professor (he 'wrote the book' on federal income taxation that's used at law schools all over the country), so he understands finance/investing better than most academics.

I would guess that their net worth was north of $10M just based on those earnings, subsequent investment, and their house (which is apparently worth $3M+).

Of course, SBF has had some incredible arbitrage wins over the years, and he presumably offered his parents the opportunity to run a million or two through his money making machine. If they were more conservative with their gains that he was, they could easily have $20 or $50 million. I agree it's unlikely that they have 10 figures, though.