There are currently no Tether hardware wallets available, but starting in late 2017, AsicVault hardware wallets became available which have support for the USDT cryptocurrency. The official Tether wallet can be used via the browser at wallet.tether.to/app/, but there is also a Tether app for iOS and Android available in the app store.
I think the problem isn't so much that people don't know how and where to store your Tether, but rather whether Tether the currency will hold its promises and always pay back one dollar for each Tether. That is the major risk. If Tether collapses, billions of dollars will collapse along with it within a blink of an eye. I guess that is what people are concerned about. So far it has been holding its peg strong.