It's not a message for everyone — even though that's exactly what it's intended to be.
Many Democrats are angry. They're angry with President Trump's election and what it represents. And they're angry about the direction of the country, and the inequities in American life.
So it would make sense that the person running for the Democratic nomination for president would channel that anger. President Trump did it to win over the Republican base in 2016, saying he gladly carries the "mantle of anger."
Not Joe Biden.