Wouldn't that be more applicable to the GPU manufacturers? Coinbase is basically a bank.

Those too, but Coinbase will generate pretty constant revenue (depending on trading volume) while GPU manufacturers have the additional expense and risk of R&D, production and distribution.

Not to diminish Coinbase's work of course, they're dealing with a ton of international regulation. Their trade is probably more a legal one than a software engineering one.

Mining is a small, niche part of crypto craziness. Real action is in trading.

"Sell shovels or be the bank that the miner sells their gold to" is a bit wordy, but yes, you're correct.