That's kind of a different thing altogether though, really. The "fuck you money" generally comes only in the case of a liquidity event, such as IPO, sale, etc.

To my ear, there are compelling arguments both ways. Assuming a large company, employees 1-x should probably enjoy some of that fuck you money, but clearly, at some point there's a falloff. If my company sold tomorrow, I would not have in any way been involved in its sale. Same with an IPO. Our company has been around for years, sells expensive software, has millions in revenue, and I honestly couldn't tell you whether or not we've turned a profit yet. Assuming we have, it was probably done only last year, which meant that somebody was footing the bills of a multi million dollar company for a decade or so, and that person wasn't me. If somebody was spending millions on an idea that took a decade to pay off, then absolutely they deserve more money in a liquidity event than I do, and I'd be a fool to begrudge them that.

That said, not all companies are created equally, and many get to market / revenue / profitability at different timetables with different employee counts, so YMMV. That said, the notion of 'fair' is so abstract in this scenario then I think it's safe to assume that it is universally convoluted. Hard to pin down exactly what is or isn't fair without internal knowledge I don't have.

It's not about the amount of effort that you've contributed, it's about the amount of risk you've taken on. The larger the company gets, the less likely it is in general to fail. So of course those who join sooner get more money - they took on far more risk than the guy who joined the month before the liquidity event.