But it's also important to note that only $300K of that is in cash. The other $600K is in profit participation, which could take years (maybe even a decade!) to be realized. It could also be worth $6M a year when it's realized.
But ultimately it's an investment of your time. Or to think of it another way, you're getting paid $900K a year but you're also investing $600K a year in OpenAI, which may end up being an amazing return or nothing at all, just like any startup investment.
Although with Sam at the helm, my guess is it will probably be worth more than $600K a year.
First, ~46% of it is gone in taxes including federal tax (~25%), state tax (~8%), FICA (~4%), and sales tax on everything you eventually use the money for (~9%).
So that's 162K left. Not a lot to pay sky-high rents, car payments, insane medical bills despite insurance, lawyers to fight said bills, save up money for parental elderly care, save up money for yourself for retirement, etc.
And yeah, having kids on that money? Very difficult.
If you're not in the bay area, different story, it's a very nice income. But they probably won't give you that package if you're remote.
And if you're in the bay and not planning on having kids, it's an okay salary.