You can never protect yourself 100%. What you do is protect yourself as much as possible and mitigate risk to an acceptable degree. You can never remove all risk.

I think malware is a significant threat because the mitigation, like antivirus software, hasn't evolved to a point to really mitigate the risk to a reasonable degree.

It's actually a smarter crime because imagine if you rob a bank, or you're dealing drugs. If you get caught you're going to spend a lot of time in custody. But with hacking, it's much easier to commit the crime and the risk of punishment is slim to none.

I seek as much as I can to mitigate risk.

I could pose as a Yahoo rep claiming that there's been some sort of fault, and somebody else is getting your e-mail, and we're going to have to remove your account and reinstall it. So what we'll do is reset the current password that you have - and by the way, what is it?

Are hackers a threat? The degree of threat presented by any conduct, whether legal or illegal, depends on the actions and intent of the individual and the harm they cause.