The far left believe that you should not be able to keep the money you work for. They believe they have a right to use the government to steal the product of your labor.
The problem is once the government starts stealing from those who work, they stop working. When everyone stops working, the government has to force people to work. And once government leaders use force against the people, they can never give up power again for fear of retaliation. That is how socialism turns into National Socialism and Communism.