A few things I have noticed missing from discussion of why/why not to join a start up is prestige and lineage. Early engineers from start ups that get traction carry an aura of prestige (warranted or not is a separate question) that they were witness to 'something special' that happened.
Second is lineage. Like it or not, cohorts of engineers often stick together and create informal networks that help populate their careers with better opportunities in the future. Going through the crucible with a team is a great way to form bonds that can last decades.
The first part I’d say is even less likely than a big payout. That is only going to be true if it’s at a very well known consumer brand or just within a very specific niche
Second is lineage. Like it or not, cohorts of engineers often stick together and create informal networks that help populate their careers with better opportunities in the future. Going through the crucible with a team is a great way to form bonds that can last decades.