Under what circumstances, outside of violent or illegal behavior, would an international student's visa get revoked?

I think that if you put any false information on your visa application then you could have your visa revoked at any time.

A student visa can get revoked for a number of reasons...not attending class, working illegally, etc. The rules have become quite strict in recent years.

I guess the rules are becoming less strict now. Most of the international schools have seen a significant drop in the students turnout and there are now more incentives offered to international students to pursue education in the country.

This must be based on a foreign student's home country. Some people have an easy time getting into US colleges, where others seem to experience greater difficulties

The US dollar is very low compared to some major currencies such as the Euro so many parents are now sending their kids to college in the US. In many cases it is cheaper for a student to attend college in the US then in their own home country.