Trump isn’t adding to his base either. a lot of independent voters think Trump is corrupt. he is not very popular outside of his base. Biden’s strategy is run on anger at the abortion decision and “saving democracy” which might be enough to put him across the finish line but it should be a blow out for democrats if someone who wasn’t Biden was running against him.
The trolley problem makes sense in the context it was developed for, which is to be an ethical thought experiment. It’s got nothing to do with politics unless you’re just a lazy thinker (which Biden fans pretty much are.)