A founder takes far more risk than an employee. It's easy to look at extremely successful outliers and say in retrospect that they are unfairly wealthy, but for every Sergey Brin or Elon Musk, there are many many people who slave away at a company for years at a very small salary, burning through their savings and getting loans (or "investments") from friends and family.
Take Jeff Bezos. He was a fairly wealthy guy, having worked at D.E. Shaw before founding Amazon. Still, he took a $250k investment from his parents to help found the company. Yes, it turned out to be a great investment, possibly worth $30 billion today, but at the time, the more likely outcome was that it would be worth $0. So not only did he risk his own money, but that of his friends and family on his new venture.
Contrast this to an early employee who starts after the first round of outside money is made. That employee often gets paid a competitive salary (maybe not a FAANG level salary, but something that's fairly easy to live comfortably on). They certainly are not expected to raise money for the company. It's just a much safer thing to do, that really doesn't involve nearly as much sacrifice as the founder.
Now, I agree that there is a point where the rewards may not justify the risks, which is joining a company in the pre-series A stage. At this point, you might be asked to take a very significant salary/benefits cut, while your share of the company is likely to be in the low single digits (percent-wise). At that stage, I personally don't think the risk/reward ratio is fair (i.e. i think that stock grants to these early employees should generally be higher than they are).
Take Jeff Bezos. He was a fairly wealthy guy, having worked at D.E. Shaw before founding Amazon. Still, he took a $250k investment from his parents to help found the company. Yes, it turned out to be a great investment, possibly worth $30 billion today, but at the time, the more likely outcome was that it would be worth $0. So not only did he risk his own money, but that of his friends and family on his new venture.
Contrast this to an early employee who starts after the first round of outside money is made. That employee often gets paid a competitive salary (maybe not a FAANG level salary, but something that's fairly easy to live comfortably on). They certainly are not expected to raise money for the company. It's just a much safer thing to do, that really doesn't involve nearly as much sacrifice as the founder.
Now, I agree that there is a point where the rewards may not justify the risks, which is joining a company in the pre-series A stage. At this point, you might be asked to take a very significant salary/benefits cut, while your share of the company is likely to be in the low single digits (percent-wise). At that stage, I personally don't think the risk/reward ratio is fair (i.e. i think that stock grants to these early employees should generally be higher than they are).