Tether is an alternative storage for traders and users who want to stock their asset without thinking of big loss and big gain. All the crypto currencies have a risk and you should be aware of that, not only Tether and bitcoin as they can just explode anytime like they will get a no value at all if in case all the governments will decide to banned the usage of crypto currencies.

And Tether will not be a threat to bitcoin and to all crypto that are not stable currencies because the investors will surely to look for a way in order to profit and stablecoin is not an option for them therefore they need to buy a crypto that are not stable in order to achieve their goal which to profit. That is a very simple way to eliminate the threat of stable currencies.