Usually one of three things: the ideology was shallow, the incentives changed, or they convinced themselves distribution mattered more than custody. Cypherpunk lesson stays boring and useful: build so users can exit, not so they need the founder to remain pure.

unforseen need for fiat?

Needed fiat for something quickly, that's the only reason I can think of.

They’re a fed

They needed more than $100

Purity tests are boring AF 🥱

Buying a house. Leave it in Bitcoin till you know the cash amount needed. Other option would be to slowly sell for cash, but that is a lot of cash to carry around. The bank or title company are certainly going to ask where the cash came from. Thank you AML.