> their price stays the same.

TerraUSD enters the chat

You're right that they aren't speculative in the financial sense of "hopefully gaining value over time", but you do speculate (in the more general sense) on the fiat-pegging mechanism(s) to work to preserve the value you are storing in them...

Sure, in the same way that holding USD is speculating that the government won't halve its value tomorrow. There's speculation, and then there's speculation.

There are different flavors of stablecoins though. There's the ponzi scheme flavor that is propped up based on hand waving alchemy, and there's the boring (and now regulated) flavor that's actually backed by real money.

And who is the authority to prove which stablecoins are ponzis and which are 'backed by real money'?