Equity is skin in the game. Why are you implying that a well paid engineer, in both salary and equity, would be treating their start-up role as a 9-5 bank job?

Equity is skin in the game. Why are you implying that a well paid engineer, in both salary and equity, would be treating their start-up role as a 9-5 bank job? At the very least a startup is not as safe a bet as a stable job at a big company like that. With equity they're going to want to work hard to increase the upside of their contributions.