There's certainly some types of startups where the risk rationale does apply. For example, the founders who went with zero pay for two years and got an early working version and happy customers before hiring their first employee. Yeah, those founders can justify their big percentage.
But the Silicon Valley mold is: a couple of guys quit their jobs, hit up VCs for a month or two with the roughest sketch of an idea, get funded, and hire their first employee a couple of weeks later. That employee gets maybe 1% maximum, or the order of 1/50th or less of what the founders. Meanwhile, the engineer will bust his ass, show up at work every day and code some more at night, debug on weekends, etc. "We're all in this together, team!"
Then on the happy day years later, the founders start pricing out their MacLarens, while the engineers blink "WTF" at their actual payout.
But the Silicon Valley mold is: a couple of guys quit their jobs, hit up VCs for a month or two with the roughest sketch of an idea, get funded, and hire their first employee a couple of weeks later. That employee gets maybe 1% maximum, or the order of 1/50th or less of what the founders. Meanwhile, the engineer will bust his ass, show up at work every day and code some more at night, debug on weekends, etc. "We're all in this together, team!"
Then on the happy day years later, the founders start pricing out their MacLarens, while the engineers blink "WTF" at their actual payout.