Long story short, casino owners, agriculture (much of the farm land was owned by US corporations - mostly sugar), oil companies were friends with Washington during the revolution, Castro was not. He also wanted to nationalize oil, reform agriculture, etc... Ike and JFK gave him the cold shoulder and worse (bay of pigs) to protect the interest of the corporations. After continuously being kicked to the curb when trying to meet with the US presidents, the USSR saw this as an opportunity and showed up his door step offering billions every year if he would turn communist. People forget he never declared the revolution socialist until years after it was won (although he's always had some socialist ideals not unlike other politicians all over the world). Next thing you know, there are Russian nukes in Cuba, more embargoes, and the whole thing goes down the shitter.