Fidel never told most of his followers he was a Soviet tool until it was too late.
The general feeling of the time was, the ideology was not bad, it was just perverted by a few rotten apples - get the right leaders and the perfect socialist society will emerge with a lot of hard work.
When things ran downhill, people began to see not even the leaders’ best efforts could improve the situation. The ideology didn’t work no matter how people tried hard to make it a reality.
At some point one had to say Communism isn’t the solution.