External impression, not facts, but intuition seeing how some VCs and startups are acting:

He didn't seem to have a real choice, maybe an illusion of choice since (from an external point of view) as he was pinned against the wall.

They were using his software commercially and even using the trademark of Salvatore (he was complaining about such uses occasionally). He was broke, I guess that's why he didn't register the trademark. Literally while they raised 40M USD, he was explaining struggling on this board:

https://news.ycombinator.com/item?id=12506743

This is actually one year after the first Redis Labs deal :/ Totally not the speech of someone with a multi-million exit in sight.

Fast-forward several years later: https://news.ycombinator.com/item?id=19203596 (with already >1B valuation)

If Salvatore just got 10% of the company he would get 100M+ USD. 1%: 10M+ USD.

Something must have happened.

If I'm wrong and he is super rich, then it's my mistake, but in general it's incredibly easy to get screwed up in a hostile shareholding / corporate environment when in front of you you have experienced lawyers and bankers.

As long as the stock is illiquid you aren't really settled, are you?