Because so many trump voters are low-information, rabid and impervious to fact and/or reason. They will vote orange even if he shoots someone on Fifth Avenue to death, or if there are 32-or-whatever felony indictments/verdicts.
Meanwhile, many potential Democrat voters are also low-information in their own way - impressionable, fickle and with little memory retention, they seem unable to act upon a clear and present danger until it punches them in the goddamned face (and by then of course it’s too late), somehow have normalized the orange threat and are easy prey to an algorithm pushing a “both parties are the same” divide-and-conquer propaganda.
The difference between a parasite-laden excrement chip cookie and a raisin oatmeal cookie, “But I wanted chocolate chip! bOtH cOoKiEs ArE tHe SaMe!”