Is there a situation where sanctions have done anything other than impoverish the general population?
I hardly think Kim Jong Un has "strengthened support" from NK citizens, bar the top elite. They just get shot if they step out of line.
Iran has a similar environment of fear, though not as totally controlling.
I'm not sure what Cuba is like for political repression, but the people are hardly supportive of the government as i understand it.
For what its worth, i don't believe imposing sanctions on Iran/Cuba is reasonable now. With the right diplomacy Iran looks to want to come to an agreement, and Cuba is no threat to anyone.
Russia is in a better position while they have support from China. But there is still an affect. Also, i don't think it's possible to happily trade with Russia as if they were an ally while Putin grabs land from other eastern European countries.
If the premise was that the governments would care about their people and give in, or the people would turn on their governments, then no, that's just not happened.
They made a deal to stop in exchange for removal of sanctions. That worked for a while but then a few years later the US reimposed sanctions claiming that the deal was not working (but was unable to cite any evidence to support this), so this time the sanctions provide no incentives.