You miss DAMunzy’s point.
Every day we get hard lefties saying they’d rather vote third party, stay home, or even vote Trump because Biden didn’t get them the shiny golden alicorn that farts rainbows that they swear they were promised. All it would take is for enough of them to vote Jill Stein or RFJ Jr. (who isn’t very leftie when you look closely at him) and Team Pepe can steal the election. Biden has to appeal to both the moderates AND the hard left, an impossible proposition, while trying to make the point that both moderates and hard-lefties lose and lose hard if Team Nazi Frog gets into office.
OP doesn’t seem to care to answer this question, so other people are trying to fill in answers as best they can.
I like mozz’s answer. The Hard Left is an amorphous concept that depends on the individual and their opinion in general. For some of us, they are the most progressive end of the left-right axis, motivated by working to protect the most disadvantaged in society. Many of these look at Project 2025 and the Trump administration of 2017 through 2020 and come to the conclusion that their priorities are best served with Biden in office and Trump on the sidelines, but quite a few get blinded by the Gaza situation and think that somehow letting Trump burn it all down will help them politically. Unfortunately, with how divided American society is, it won’t take many people voting third party or staying home, especially in Swing States, to swing the election Trump’s way.
Of course, there are people who think that the Hard Left is anyone left of Atilla the Hun, or at least anyone left of the individual in question. OP peaced out so we’re left speculating on them, but I suspect from their wording, the Hard Left is anyone left of themselves. And thus, the OP is being clued in that the Hard Left is NOT blindly voting like Biden like the Hard Right is blindly voting for Trump. Maybe it’ll be an eye-opening experience. Sorry, I can’t wave a magic wand and make OP answer this, though. That would be nice.