I believe we've reached similar conclusions for ourselves.
Short-term happiness only leads to emptiness. Material connections, giving into desires, and shallow relationships only get one so far: even if it takes 30 or 40 years. Those people you see as happy living life are living in blissful ignorance of the depressing reality around them and which they have contributed to building themselves. Those people are truly lost and the moment a misfortune happens to them they'll collapse. Nevertheless, actual fulfillment comes through living with purpose: Being able to find constructive passions, having genuine love and care of others (i.e wife, kids), etc. Sometimes fate makes it easy, but these sorts of feelings and meetings only come once. It's up to you to make do with what fate gives you seeds for; reap and sow it. If you don't, it's all downhill from there. Adult life is a really just a shitshow we're all living in and it's only gonna get worse.
I think the only reason we're all still here is because we're hesitant to actually make the jump. We like to think we can end it at any time, but we keep living through the mundane or hellish with the anticipation to keep seeing how unknown things play out. I've lived in a self-made hell for years and it'll be that for the foreseeable future. There isn't a moment where I don't pray for death, wish that things were different, and I do not understand why I haven't died yet. Yet, I'd rather not be blissfully ignorant or "normal".