Stripe made the right move here. Going public is a huge move. You don't want to make a big decision like this because early employees couldn't have cashed out.
There are lots of other considerations that come along with an IPO and Stripe is addressing the core problem (early employee liquidity) with a targeted solution.
(And yes -- they would've been better off doing two years ago. But timing is hard, and that's not really relevant to their decision now, which is the best at the current time given the past.)
I agree that decision to IPO is a massive one and it shouldn't be just driven by this specific situation, which was probably solved in people's best interest.
But, they were put into this position for waiting for too long and not going public earlier. I have a feeling that Stripe is doing a classic 'emotional investor' mistake. They are considering their valuation to be 90b+, and see this as 'just 50, it will bounce back', not considering that company went from 0 to 50b. There is no guarantee that it will go above the current valuation, and anything below that is going to be harmful, even for current employees who were saved by this move.
There are lots of other considerations that come along with an IPO and Stripe is addressing the core problem (early employee liquidity) with a targeted solution.
(And yes -- they would've been better off doing two years ago. But timing is hard, and that's not really relevant to their decision now, which is the best at the current time given the past.)