I always assumed angel investing (at least as it emerged originally) was essentially philanthropy with the motivation being it gave very rich people a way to nudge things they liked into existence and provided them with a semi-cheap way to keep their network fresh with young, hungry, interesting new people. Bonus it might very occasionally turn in to a lottery ticket (but that wasn't the primary driver of making the investment).
This seems to be a big part of it, but is there a separate word for it? It’s definitely not philanthropy because it’s not directed at public good.
Economics must have made a term for this part of the venture ecosystem. “Seed capital” misses the significant social and class aspects of the behavior.