Is there anything that makes it worse than AliExpress, eBay or Amazon?
The others were never as aggressive in their quest for monopolies and made it on some other merit. Not to say the others are much better, but Temu will have to make that money back somehow, eventually.
Basically price-dumping to destroy the competition and gain market share.
What I've noticed from Aliexpress reviews is that a lot of reviews are from places that don't have much of an Amazon footprint (e.g. Russia, E. Europe, Mid east).
The other thing is that ship-from-China circumvents a lot of duties that can be hefty on some goods. And sometimes sales taxes (not in USA anymore, but still true elsewhere).