You're lying.Well first, with or without economic sanctions they would be poor. There is zero evidence that the US caused any of the decline in Cuba. Zero. That's opinion, without a factual basis.
United States embargo against Cuba - Wikipedia
"Between 1954 and 1959, trade between Cuba and the United States was at a higher level than what it is today, with 65% of Cuba's total exports sent to the United States while American imports totaled 74% percent of Cuba's international purchases.
"After the formal implementation of the embargo and the passage of Proclamation 3355, there was a 95% decrease in Cuba's sugar quota, which canceled roughly 700,000 tons of the 3,119,655 tons previously allotted to the United States.[58]
A year later, Cuba's sugar quota was reduced to zero when President Eisenhower issued Proclamation 3383. This substantially affected Cuba's total exports, as Cuba was one of the world's leading sugar exporters at the time."