Because they hate them?

Jamelle Bouie:

Why Democrats Want to Tax the Rich

They are hung up on inequality according to Bouie, but they don't seem to comprehend that making the rich poorer will also make the poor poorer.  Through out my like I have never concerned myself with the fact that some people are richer.  I always felt that it was up to me to do the best I can with what I have.  Because some people had more money never made me feel unequal.  In my dealings with the rich I rarely cam across any who failed to treat me with respect.  If I was doing work for them, I felt it was my job to help them succeed and to prevent losses that would harm them.

I think that people who sit around upset because someone has more money or stuff than them are wasting time they could be spending in more productive things that might just make them more wealthy.

I do think that in some ways Democrats hate the rich and some rich Democrats are part of the self hating rich who think they don't deserve their prosperity.  This appears to be particularly true of the Hollywood left.  They should try investing their money and reaping profits from those investments.  They would then see just how difficult that can be.