There's more than just Bitcoin and Ethereum.
Many other blockchains were or are now just as good for DeFi as Ethereum. Or at least close enough. There's quite a competition there you seem to have missed out completely.

I don't see a good reason for Bitcoin care at all about this and I think that Bitcoin side chains has lost the train for this.
So it's imho it's closer to "failed experiment", although it's not even known enough to be called like that by such a number so it would matter...