If the amount is big, hardware wallet may be also an option worth considering, although I fail to understand why would people hold USDT, since it won't grow bigger than 1$ (stablecoin), it has issues with its backing and you have to trust the issuer (again, stablecoin).
Pretty much a hedge against volatility. Something something selling coins to buy back lower. And yea, it has it's risks in terms of the company behind it(asset backing, potential locks due to it being centralized, and such), but for some people the risks are worth it due to them not needing to touch KYC exchanges.