Why did president JFK get assassinated?

Insufficient restrictions on the sale of firearms. Since the Gun Control Act of 1968, it has been illegal in the US to sell firearms to anyone who has renounced their US Citizenship. Lee Harvey Oswald had renounced his citizenship and lived in the USSR for a few years, before moving back to the States to live in Dallas. He also purchased his rifle via mail order, which was made illegal by the Gun Control Act.