Probably not. Vast majority doesn’t think about these sort of things. And you’re absolutely right that peoples trust could be exploited in jams. It’s why I’ve only played browser versions so far as it should be safer to my knowledge as browsers are designed to withstand the web and malicious actors there. But when you play a jam game or worded slightly differently run a random software from the internet on your computer, all bets are off as it could do anything you can and way more. But magnitudes faster.
But then again more often than not the games are safe even if warned by windows defender as it will pop up a warning from anything slightly suspicious. Like when the software is not digitally signed by a company for example. Well none of us here represent a company here nor will be signing the games digitally so it will most likely look a little suspicious to some antivirus software and trigger a warning.
That all being said. Stay safe out there. If in doubt, don’t run the game just like with any other software. Doing a little research on the creator is a good first step. If they have been around actively for a longer period of time, they are more likely to be random dev just participating in a jam with no ill will.
ps. VMs would be good but highly impractical for majority.