However, sanctions have had limited and uneven effect on nations. In some cases, they had zero effect as those nations were simply supported by different regimes. The study of political transformation has a rich and old history.
Political leaders of sanctioned countries mostly die from old age while still in power, and the effect of sanctions are mostly felt by ordinary people who struggle through life without access to technology, medicines and basic commodities that we take for granted in most countries. Sanctions also undermine patents and copyrights, since those being sanctioned will often find ways to copy the products that they are prevented from buying.
When all that is said, I try to avoid buying from corporations with industrial practices that are harmful to the environment or who abuse their employees. Corporations are in many cases much more powerful than nation states these days, and as opposed to most politicians and emperors, they read the bottom line of their annual report with a microscope.