I tend to be a bit isolationist myself, but as
@arthnel mentioned, sometimes the fight comes to you. I know many in the world regard the U.S. as a bully, but from our perspective, we (the people) do care about trying to ensure that the world is a more stable place. In retrospect, it appears that some interventions (those of other countries as well, not just those of the U.S.) have exacerbated the problem, but as the saying goes, hindsight is 20/20.
If everyone were living peacefully in every country, there'd be no need for military intervention, except for profit, or just to stir the pot, of course. There are bullies in every society, and if one group wants to bully/terrorize or deprive others of rights, there will probably always be another (person/country/coalition) that feels it needs to step in and intervene.
I agree that humanitarian aid is needed, but I don't think it's enough for a country to simply throw money, supplies, food, etc. at the problem while other countries are doing the dirty work of sending troops to die. "We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm." - Winston Churchill