It is both.
A LOT of the US voters want exactly what Trump is saying. 77 million adults heard all of his fascist rants, and said "That's my guy!" Also the majority of people who voted Biden, then sat out this one, are older, white, men.
The DNC also aren't messaging to the people who don't like the GOP, they are messaging towards those who are statistically most likely to have voted for them in the past, and are most likely to vote in general. They also are watching what the GOP is saying, seeing the rabid fervor their bigotry elicits, and work elements of that into their messaging, because it's working for the GOP, thus it's working.