Would you leave big tech for a founding engineer role?

2 YOE at big tech, $235k TC, good WLB. I have an offer to join a startup as a founding engineer / third engineer, but cash comp would be \~35% lower. The startup is pre-revenue but has 1M+ MAU and seems promising (completely bootstrapped but did big pre seed round). I’m trying to understand the long-term career impact. In 5 years, which path is usually stronger: \- staying in big tech, getting promoted, and building depth \- or joining very early, getting broad ownership, and learning faster? Also, if I do the startup route, is it harder later to go back to a larger company in a normal senior IC role? I have a big concern that 5-15 years AI probably won’t take out dev jobs but increase dev productivity especially for full stack engineers to the point where it will be very competitive over saturated market. Is this a legit concern? Wouldn’t joining the startup help diversify my skillset and set me up for future career success or is it better to just stay in big tech? edit: I appreciate a lot of the concerns regarding being a founding engineer. I appreciate the valuable insights. I’m more concerned about the prospective AI boom that might not take our jobs but increase productivity to the point that career will be stagnant or market will be over saturated in 5-10 years If I was a devops, ML engineer it would be a different story. But currently working as a full stack, api, and some infra stuff (AI enabling us to dabble in everything lol)