Assuming they're 40, how far do you think $250k will go 20-30-40 years from now? It's not a stretch to think dollars could be devalued by 90%, possibly even worthless, within 30 years.
They obviously don't keep it dollars. Diversify into equities, property etc.
I love how the comment I'm responding to literally says "then collect $250k per year risk free after taxes," and then you all pile onto me with downvotes telling me that's he's not just going to invest in treasuries (which is exactly the implication of HIS comment and not mine).
If portfolio is diversified enough it can be enough for decades? If dollar goes down some other things will go up. gold, Bitcoin etc.
The original comment was premised on them being income-generating assets, which gold and btc are not