They thought they were risking 13% of their collateral in the event of a liquidation - not 100%. They were risking way more than they thought.

No one lost 100% They lost their collateral and got to keep the loan the took out against it.

If I stake $2000 of Ethereum, and in return get $1500 in a stablecoin, when my $2000 in collateral gets liquidated I still have 75% of that in the loan I took out and can walk away.

The people with the 100% loss story are being deceptive

That's not the complete story. They have lost one asset with a certain set of liquidity characteristics, and unexpectedly gained one with another set.

There was nothing unexpected here. Users traded their eth X days ago for dai, with the full intention of adjusting their liquidity characteristics

What happened here simply precluded the possibility of the reverse trade when the loan became under collateralized, this was not unclear to anyone involved

Traded? You mean loaned. That was always the wording that was used to promote DAI, whatever the underlying transaction might be.

Users didft "loan" their lost ETH, they traded the ETH in as collateral and took out a loan in DAI.

This collateral trade was made with full awareness that if the loan became under collateralized the ETH would be liquidated and sold at auction