Do I believe it, as in believe with 100% certainty it will happen? Of course not.
When it is a matter of sufficient severity, do I treat it as a threat worthy of our attention? Hell yes.
If the representation is "man, Brisket, if I ever met you in a bar, I'd probably punch your face in," I'm not terribly alarmed (shit, I've met me -- I probably couldn't blame you). If the representation is "Brisket, I am coming to your house tonight, at [my actual address], and I'm going to kill you and your wife as you sleep".....yeah, I'm legit alarmed. The severity of the outcome at risk absolutely figures in to how seriously we should take it.
"Hey, I intend to eliminate all human life, and here's how I'm going to do it," said by someone who has even an outside chance of accomplishing it? Fucking pay attention to that shit.
Jesus tapdancing Christ, we've spent the last 10+ years having person after person tell us we're being alarmist when there are threats to do things like, oh, I don't know, end birthright citizenship, repeal Roe v. Wade, use the DOJ as a personal law firm to pursue one man's vendettas, etc. etc. etc.....only to be fucking right about all of that shit. So, fuck your "you're just being alarmist" shit when there are billionaire oligarchs saying "Brisket, I am going to make sure your kids are unemployed, and unemployable, and have no means to make their way in this world." That's a clear and direct threat against my family and all of humanity. Take it fucking seriously.