Exactly this, it's a very adversarial environment with huge stakes for those that can exploit it. Even projects that have been around for months, years can get exploited which is why I'd recommend waiting a long time before putting non-trivial amounts into any smart contract or crypto related projects.

That's also a big plus for Bitcoin, because it's been around the longest and because it's so much simpler than more complex chains like eth, it's as secure as it gets.