In the crypto world, everything is massively manipulated and people on the outside can only guess at how things really work.

Theoretically, everyone buys and sells Tethers, but they just trust Tether so much that any time the price starts to drop below $1, clever people rush in to buy it, knowing they will later be able to sell it for $1.

Actually? Tether itself is probably buying those many of those Tethers to keep them at $1, and buying large numbers of them, and if they ever stopped the price would collapse.

But it's impossible to know. The crypto world is a crooked casino, and you know everything is fixed but you're never sure exactly how. Is the blackjack dealer stacking the deck against you? Are the slot machine payoff tables completely different from what they say? Are the big winners secretly working for the casino? You never really know.