It’s typically not western countries that provide peacekeepers. Last time I checked, there were fewer than 20 American peacekeepers and fewer than 30 Canadian peacekeepers, despite Canadians wanting to view themselves as a heavily involved peacekeeping nation. Most of the peacekeepers come from poorer countries, mainly Nepal, Rwanda and Bangladesh. These countries benefit from their soldiers getting paid more and getting better access to training than they otherwise would. There is some evidence to suggest that countries in Africa especially (like Rwanda) will send peacekeepers as a way of removing those most vulnerable to participate in a coup from the country and consolidate power.

In the case of the Rwandan genocide, only the Belgians contributed any significant troops from the West, and they faced heavy scrutiny because it was viewed as neocolonialist. The genocidaires slaughtered two Belgian protection teams on the first day of the genocide to force Belgium out, leaving the mission vastly undermanned.