Ok, I'll be kinder, replace "stupid" with your choice of "confused", "misled", "apathetic", "fooled", "uncaring" etc.
The point is that when you look at his statements and "policies" with an objective lens, they will either not achieve the desired outcome or will actually achieve the opposite.
Add to this the proven 30,000 lies he told in his first presidency, his felony conviction and all the other charges, his terrible behavior to women, his multiple bankruptcies, the close relationship he has with white supremacists and other nutjobs, his admiration for dictators, and his handling of the pandemic which resulted in hundreds of thousands of unnecessary deaths.
So to give him your vote means that either you know all that and still approve of him, which says something about your own character, or you don't know it, which means you're ignorant, or you don't believe it, which means you're a tin-foil hat wearer, or you accept it all but still think somehow he's better than Kamala, which leads back to stupid, or you're not interested in all of it but think he'll be better for your own bottom line, which makes you either apathetic, misled or uncaring.
It appals me that over 70 million people fit those categories but I have a hard time thinking of any other explanation.