Yes, tether (and usdc + dai stablecoins) relies on ethereum for security.
Edit: this is one of the reasons I’m optimistic about the future of ethereum. The stablecoins have become so critical for defi that it’s hard to imagine another platform (like polkadot) gaining critical traction needed to overtake it.
Serious question from a crypto noob - what's the point of defi systems if they're all built on stablecoins and depend on the value of a fiat currency at the end of the day? Especially for permanently-deflationary coins like BTC?
Cynical take: a lot of it is effectively financial cargo-culting -- building structures which mimic traditional financial products, like banks, loans, and investment funds, in the (fruitless) hope that this will create value.
I thought the same thing about NFT art trading. But if everyone is part of the cargo cult and the cult is making real money then is it still a cargo cult?
One of the stories about how cargo cults were first noticed was someone needing to do an emergency landing, noticing a runway that wasn’t on their charts, landing, and finding the locals had built it so that aircraft full of cargo would land on it.
Given it was successful despite being a cargo cult (the plane landed QED), by symmetry the ability to make money with cryptocurrency doesn’t make it not an economic cargo cult.
(One must do more that this to show that it is a cargo cult, rather than that it is still possible for it to be, which I say despite liking the cargo cult comparison and being generally very against cryptocurrency).
They're built on Ethereum, not stablecoins. The stability of the network currently relies on stablecoins only in the sense that people use stablecoins to store wealth in situations where fiat is more stable than crypto.
Edit: this is one of the reasons I’m optimistic about the future of ethereum. The stablecoins have become so critical for defi that it’s hard to imagine another platform (like polkadot) gaining critical traction needed to overtake it.