> I know people who were formerly software developers and who stopped their careers to become stay-at-home parents.
The population of people who consider $150k a year not to be sufficient incentive to get a job is vanishingly small.
> As for past investments in different careers, those are sunk costs and irrelevant to decisions made now.
It's not irrelevant if they did those things instead of learning/doing software engineering. You can't study medicine or law or banking for 8 years and just become an engineer at Google overnight because the Google starting salary had (hypothetically) risen to $300k and it's now a better deal.