Capitalism is fundamentally wrong becuase it is based on the exploitation of the working class, i.e. nearly all of us. Imagine a Capitalist sells a smartphone for $500. I'll be generous and say the raw materials cost him $100. The labor cost let's say is $50. I'll even allow him $50 for marketing and overhead. That leaves the Capitalist with $300 which he has stolen from the workers. The people who made the phone donated those $300 of their effort to simply enrich the Capitalist. He himself did nothing to earn that money.

Regarding "revolutionaries", it is painting with far too broad a brush to condemn all of them. Gandhi and Che Guevara come immediately to mind.