It is good that up until now, after 5 years the OP posted this thread, tether is still standing up.
But I won't suggest to hold this for long term because one mistake from the Tether team or major hacking and we may see this crumbling.
Just keep your funds safe and as much as possible diversify your portfolio. We can't trust them to fully respect their promises.
The risks are simply to high to ignore. Tether may have been standing for a long time, but that doesn't mean it's "invincible". As I've said before, a government crackdown or a massive hack could put an end to Tether for good. People are foolish enough to trust their hard-earned money on a centralized stablecoin subject to manipulation, corruption, and fraud. Trusting Tether is no different than trusting banks (but even worse). Crypto behaves in many strange and bizarre ways, so no one can exactly tell what will happen with Tether in the future. What's important is to diversify your investment into other crypto assets in order to protect yourself from the risk of loss. As long as you do that, you'll have nothing to worry about. Just my thoughts