They push this message hard: unless you pay us, the bad guys will eat your lunch.

The truth is that if you uninstall their software (and hopefully also if you just let the trial lapse, though I don’t actually know whether Defender Antivirus gets enabled automatically in that case) Microsoft will defend you against the lunch-eating bad guys just as well as McAfee, for free.

That easily qualifies it as fraud.

For that reason, I’m willing to call it a scam when preinstalled or otherwise installed without user intent. I wouldn’t call it a scam if people installed it deliberately (though I would still disparage it and its tactics).