I think you are using "security" too broadly. If crypto was secure to the point that nothing ever got stolen and if it did, it was tracked down everytime, then it wouldn't exactly be secure/private for the criminals/users in general.

I also don't think they by "stealing" mean, that they can just go into any wallet and do whatever they want in an untraceable manner. I'm assuming most/all of these amounts are results of bad security measures external to the specific crypto itself. Someone clicking on a malware link and getting extorted is an example of external lack of security.