Yet the ruling elites and military still enjoy decent quality of life, it´s mostly the ordinary people who suffer. In case of Russia that´s okay since large parts of the population genuinely support the war, but I´m not so sure about Iran and Cuba, where most are not supportive of their governments anyway.
The point isn't necessarily to make leadership suffer, but rather to prevent suffering of everyone who might be threatened by a strong Cuba/Iran/North Korea
In case of Cuba I think the sanctions regime is in part motivated by vindictiveness and in part to make an example for other nations in the americas of what happens when you evade US hegemony..