Sanctions are there to cut off 1-2% of GDP each year from the dictatorships' economies.
Over 30 years that turns countries into harmless (to the West) backwater shitholes.
The consequences towards the local populations are just a side-effect (sometimes wanted, sometimes not).
You cannot expect people outside of your dicatorship to prioritize your well being over their own safety. It's on you to fix your country. If you won't - people will isolate you to keep their countries safe.
Can't really blame them.