Sometimes those underlying conditions are brain chemistry though. The pills work for a lot of people. My Bi Polar depression doesn't seem to stem from any trauma or anything. I've done therapy and it did nothing. I've tried exercise, it helps for a short period. I tried diet, seems to help a little. If also tried about 15 different medications before a found a combination that keeps my mood fairly stable.
I almost killed myself before I found the right combination of meds. Meds work for some people we shouldn't be so quick to discourage it.