Sanctions are a modern form of siege warfare that affords western regimes a path towards murdering innocent people while their morally bankrupt public looks the other way.
That is a misrepresentation and over simplification of a diplomatic tool. There are many kinds of sanctions and they are put into place for many reasons. Why should we let dictators use our financial institutions? Why would we let corrupt individuals use us to enrich their selves at the cost of their own people? Why would we not use our influence to push for fair, democratic elections?
Your questions cannot be answered because they assume things about the world that are simply unreal and/or are not even logically consistent enough to be real.
For example, the most corrupt people on the planet are USA politicians. They are immune to insider trading, they have legally structured bribery, they receive bribes totalling in the billions annually, the parties literally contribute to their opponents' campaigns, they control the entire debate system and establish a quid pro quo to require compliance from candidates in exchange for air time, they literally create and maintain prohibition laws to increase profits for private operators of their prison services....
As for dictators, the USA imprisons more of its population than any country in the world. It imprisons more people than the USSR GULAG did at its height, and they were holding Nazi soldiers. The USA prison system produces $11bn of goods and services for private companies using slave labor. Prisoners in the USA are usually charged anywhere from $100 to $350 every day they are in prison and they leave prison with that debt. That debt becomes the pretense for probation, where ex-prisoners who have served their sentences are directly surveilled and are required to work to pay their debt off. Failure to behave can result in a court summons and failure to attend that court summons for any reason can result in further jail time.
And that's just the prison system. There are political prisoners in the USA held for years. There are secret military prisons. Children at the border of Mexico are held in solitary confinement causing permanent brain damage. White refugees are welcomed with open arms. Haitian refugees are met with cops on horseback and bullwhips. The secret military bases are on foreign soil so that the USA can break it's own laws without oversight or consequence. The USA is spending a trillion dollars expanding and upgrading its nuclear weapons. All the while there are a million homeless people and budgets to address homeless are all given to the police to break up encampments and displace homeless people, the citizens pay the most in the world for health care and gets the worst outcomes, the political leaders take citizen money and give it directly to corporations in ways that are completely unnecessary to achieve their outcomes, and citizens who protest are beaten, kidnappped, blacklisted, monitored and surveilled, while citizens who kill protestors are protected and rewarded.
And you don't think the USA is a corrupt dictatorship of the land owners over the masses?
Meanwhile, former President Carter has been at the forefront of election monitoring around the globe. Out of not quite 300 countries his group monitors 90+, so about a third. He has stated, the former USA president has stated, that Venezuela had the absolute best fairest most democratic elections they had seen. And Venezuela got sanctioned for dictatorship, corruption, and unfair elections.
There is no answer to your questions because your questions assume a fantasy world that does not exist. Come back to Earth, dig into what you're observing, learn about what's really happening.
The outright stated goal of sanctions is to put pressure on the people of a nation to destabilize the government and foment rebellions. They admit this. It's warfare.