It's a wide ranging thing. Lost all 7 swing states. Lost popular vote. Worst ever party approval rating.
Some things are easier than others.
The first step is always admitting there's a problem.
Look at the issues where Trump's positions are popular. Immigration. Take a look at the Laken Riley Act. Every D swing state Senator voted for it, and also the two NH senators. They can see which way this thing is blowing. There's no reason that every single other D Senator voted against. It shows a lack of understanding of the current political environment. It should be ok to say that if you are here illegally and you're arrested for burglary or theft that DHS will detain you. Dems don't have to be the party of "law and order", but it can't be disregarded. Look at NJ, NY, Illinois, California. All those states moved far to the right this cycle. I would say part of that has to be the deteriorating conditions in their urban centers.
What part of the coalition do you lose if you modestly tougher on crime and immigration?
Hispanics? They're already halfway out the door, especially in the places you'd think the opposite would've happened. That's a red flag right there.
African Americans? I don't think you lose them.
College educated? I don't think so.
So why maintain this stance?
No
Unfortunately the simple answers look easy right now. Have to watch and wait for mistakes and pounce.
Otherwise, the gender gap is also a problem. I'm not sure how the message delivery can be tweaked to appeal more to younger men. The PC/scold thing isn't working.