I agree with you that war can easily become unpopular and turn people against their government. But is there any country, whose economy has been sanctioned by the foreigners and crippled by it, where the people then decided to overthrow their government? As far as I know my history, no. Foreign sanctions easily give every country an easy excuse to blame all economic problems on the foreigners. In every instance, they've actually united nations against their "common" enemy (i.e. the foreign sanctioner). They also provide an excuse to stifle criticism using state powers as any criticism on the government handling of the economy can be conveniently labelled as speaking the language of the "enemy" and / or supporting the "enemy".

While I understand that the true purpose of sanctions is to weaken a country's military, sometimes I do wonder if it is a war crime as it also ends up effectively "punishing the people".