I can see how it's less obvious for people, and it is important to bring these things up. They will inevitably help someone.
Also man, that second point really hits home. I've had a total of 8 'friends' over the past 10 or more years. Of that, I would consider two of them to be close, intimate friends. And they're both located hundreds of miles from me. One of them is NC with me, as we both accentuate the depressive nature of one another.
The only really rewarding thing I experience is video games, because I enjoy competition, and regularly hold top positions over others. It's also the major distraction from depressive thoughts I have. I also have hallucinations / extreme paranoia when away from a computer for too long.
The only real release from my depression I feel is being free enough to feel what I please at any time, which is impossible, or to achieve the un-achievable.
To put it into a very high-level form, I enjoy learning about anything under the sun, so much so that I wish I could solely dedicate my life to it. However the nature of our world leads to complications: money, family, jobs, etc. That's just something that you have to expect. These things are manageable. What chance within those constraints of society, humanity, and more can you expect to discover or create something that transcends history, to be remembered forever? What about affecting the world in a positive way enough to affect the coming generations into a mindset where knowledge comes first, with no border to access it, with the same plan to better the universe?
Such things aren't possible. No single human can have such an effect on the world. So personally I have to make a choice to attempt the impossible every day, trying to work on projects that might some day better our existence, or just give up.
I feel a good cutoff age for me is 29. If I don't like the direction my life is going by then, I'll probably take steps to make it not exist, or I'll continue.
I don't want to push my views on anyone, and would urge anyone that has the same ideas as me or has felt this way before to seek some form of treatment. It does help, and can get you out of a slump.
I've lost friends, family, jobs and more due to the way that I feel. I've spent days not eating or drinking laying in bed crying, waiting for it to end. If you think you need to seek help, do so.