This is a bit complicated:
Cuba was under Fulgencio Batista's reign by the time of Castro's rise. Cuba was a capitalist country at that point that was basically the US' puppet. Fidel Castro and his "guerrillas" were obviously against the system that was being employed for many reasons. I believe one of the main reasons was that Batista's Cuba was a corrupt one. There were many under-the-books assassinations just because they were a threat to Batista, etc. Overall, Cuba was a very corrupt and injust country at that point and that is why Fidel decided to fight against it, beginning with the "27 de julio movement" alongside Ernesto "Ché" Guevara.
It had a very positive impact because the 1920's was when many new technologies were introduced, one example being the the assembly line, which made many industries more productive and profitable.
Hope that helps!
