Redeem iAssets not possible?

Im trying to understand the model but struggling.
If I bought IUSD on a dex or ended up with bag from a liquidated loan for example - Its not possible to redeem any iAsset like it is with DJED, WBT, etc…?
The only option is secondary market on a DEX ?

If so then are holders not entirely at the risk of this market drying up and being left with a worthless token ?
Sorry to ask - just need to understand the model
thanks for any help

Answering my own question here - I know its because they are synthetic and not wrapped but wont this lead to the possibility of just printing an infinite anout of iAssets ?