Some of the most depressed people I've known are people-pleasers who do little more than help others.
I wouldn't say most depressed. Certainly the co-dependant types who feel obligated to serve others have a problem. People take advantage of their kindness and use them. If these people pleasers are looking for some return, "what's in it for me", that's when they get depressed, because they aren't getting it back. Someone like Mother Teresa didn't expect anything back and she was happy to serve. People in general that help others without getting anything back and demonstrating Agape love. This is a pure godly love which has no strings attached.
Depression may have
medical reasons.
Take a pill to feel secure and happy, remove pain and sorrow, etc., is not solving the core problem, it's just masking it, drugging by dulling the person. Might as well smoke a joint and forget about it. Wait, now they are administering that as well for all sorts of pain and suffering.
Basically, there's a lot of junk inside that is defective, like a disease. Other people's junk effects us as well. The only way to remove this junk is by forgiveness --God's forgiveness. Yet even after we are saved, Christians still struggle with the flesh (where sin dwells). It takes work to mortify and die to yourself. Bad habits take a while to break. We can change with God's help, but left to ourselves, at best, you just survive without hope and purpose or meaning.
As a Eudaimonist, I think the greatest moral achievement is the flourishing of the individual in this life, which requires such means as rationality, good character, and friendship. I'm also a nontheist.
Rationality, character and friendship are gifts from God. These are things he works on to grow in your life. But without Him, you don't flourish --you just grow old without hope, chasing after the wind and then die. All the stuff you gained in life will have been forfeited and lost. And so the questions for atheists are: Why live, grow, mature and gain all the wisdom and knowledge or achievements to just lose it all in the end? You think you're just passing stuff on to someone else? But they die too. So will you say on your last day? What was your purpose in life and what did your life mean?
The Christian perspective is that the meaning and purpose of life is that we reconcile with God through Jesus and gain eternal life --then everything that you've learned in wisdom and character, the invisible you is not lost but passes on. That's something to hope for and look forward to. That is part of the pursuit of happiness, the core of joy, a relationship with GOD! If this doesn't happen, then it doesn't matter what you do. If you think it's survival of the fittest, then a turtle got you beat.