a) The target country just allows their citizens to feel the brunt of the sanctions while the ruling class hoards resources for themselves.
b) The target country starts a propaganda campaign to blame the sanction-issuer for all their problems, which the citizens mostly believe.
So ultimately you end up with regular-Joe citizens in the target country having a worse quality of life, while also being led to believe that your country is the evil one.
Another poster hit the nail on the head: the politicians in the sanction-issuing country need to be seen as doing something by their populace, regardless of what the result of that something is.
Because it's at least partly true. They are the ones issuing the sanctions.
But the reality is probably more like the top levels of governments bullying, and they don’t give a flying fuck about the impacts on the average citizen.
That it will impact the country economically and hopefully result in the Government changing coarse or for the People of the country to not want to live in a shitty place with a poor economy.
I find sanctions vastly better than the alternative at that level, which would be some sort of blockade or other military intervention.