Iron/Titan did not have any such high apy and still collapsed. In case of terra, I concur that the driving force was the Anchor ponzi, but it was the mechanism that failed.
Iron was explicitly under-collaterized, and it was also trying to lure stakers by providing yield-farming. DAI is the opposite, stakers pay the stability fee to open a vault.
It did have a yield-farming component (you could mint DAI at 1% fee and put it in the DSR that would pay 2%), but that got completely knocked out in 2020. That crash was already a quite expensive lesson (tens of millions USD) for the MakerDAO team, and a lot of the investors had accepted a haircut in order to bring DAI back to the peg.
To repeat: I am not saying that DAI is bullet-proof. What I am saying though is that all the reasons you are using to make your case do not apply to DAI as it currently works.
And so did Terra. They held AVAX, BTC, LUNA and a little bit of USDC.
>150% at a minimum
And for Terra this was 100% at a minimum. It makes 0 difference.
>independent from one another
Cryptocurrency are extremely correlated.
>it managed to recover
UST itself had recovered from a previous depeg event