Several reasons:
They want to destroy the free-enterprise system and implement Communism, plain and simple. They also want to emulate the crime-control policies in Caracas, a huge success of Bolivarian socialism. Looting and burning stores accomplish all of the foregoing objectives. And enough Americans support the anarcho-Communist insurgency that they just might win the next election and oust Donald Trump.
Regardless, we should brace for a violent winter of depredation. If Trump wins, however, then he might get the opportunity to name a Supreme Court justice or perhaps even two or three, who in time might read the Constitution to discover a right to life, even for unborn babies. The party and culture of death already rue that future day.
I think they share a mindset.