Coinbase wasn't an IPO, they didn't create any new shares to sell as part of going public. They did a DPO, Direct Public Offering where they listed the existing

Coinbase wasn't an IPO, they didn't create any new shares to sell as part of going public. They did a DPO, Direct Public Offering where they listed the existing private shares publicly and allowed most shareholders to sell immediately from day one. It was a great way to make the founders rich, VC to cash out their initial investment, and... well mostly just that.