No, checkout decentralized finances (DeFi). You are leaving your money with an smart contract, which is an inmutable piece of software.
"They" didn't solve that problem, it is not the solution to all problems in finances. So, whats your point? Vaccines does not prevent 100% of infections, does that means that they are worthless?
Nirvana fallacy: https://en.wikipedia.org/wiki/Nirvana_fallacy
You said that the contract, i.e. the software, is immutable. This means that it can't be patched. If it can be patched it's not immutable, excepting semantic trickery like each version of the contract being immutable while what "the contract" points to can be changed in order to patch it.