Why would I be a “believer” or missionary in a for profit company? It’s a business transaction. I give them labor and they give me money.
Selling my “equity” in a private company once it vested wouldn’t have been an option.
Note for those who don’t know: Amazon has a 5/15/40/40 vesting schedule with their first four year offer. The first two years you get a large pro rated cash signing bonus to make up for the back heavy vesting.