I think it's the other way around - we comparatively hear a lot more about the successes than the failures. For every unicorn that made 400 people millionaires there are probably >1000 startups that either went out of business, never had a liquidation event, or never at the scale that rank and file employers got anything significant.

Obviously not literally "nobody", someone at some point joins google/microsoft/facebook/amazon/etc at an early stage and exists a millionaire many times over. Just like every week somebody wins the lottery. It's just not as likely to happen to you personally as the people selling you on joining their early startup would like you to believe.