不收費就得看spread到底是多少了。coinbase炒幣比較垃圾，但是on/off ramp usdc還是需要的。

Fidelity Digital Assets will collect a spread (assessed at no more than 1%) calculated as the difference between the price at which you buy or sell crypto in your Fidelity Crypto account and the price at which Fidelity Digital Assets fills your order.