The question is which is more secure...
storing $10,000 USD on coinbase or buying $10,000 USD worth of USDT Tethers and moving them to a wallet? I've heard a lot of things about Tethers being made out of then air.
Yes, you heard it right.
Tether is made out of thin air and can co to zero in no time.
People are for now just blindly trusting a shady company involved in a few dubious affairs that claims it will keep the price at 1$.
Of course, coinbase is not a bulletproof exchange and it might get hacked or "hacked" but still it is miles away in terms of trust.
Personally, I wouldn't hold my coins in either but if I had to choose it would be coinbase, no doubt about it.