Capitalism does not work reasonably well most the time. Unchecked it leads to countless busts and Booms that leave the average person destitute. You really should look into the history of the early 20th century. The only reason we even still have capitalism. Is because of two massive world wars. Slaughtering and grinding up many tens of millions of people. As well as passage of basic Social Security nets. We've largely at least abandoned the spirit of. If if not in practice as well.
Capitalism has been a failure at every level. Constantly. That isn't a justification or Praise of leninism. There's a lot of other ideologies on the Socialist side Beyond leninism. And they don't require large National level government. Look into them sometime.