I don't know if this will be helpful, but here goes:
I always imagine life as being full of possibilities. Now granted, things like relationships/marriages/family/bank account/legal trouble, that stuff can put a serious damper on things, and that's not even getting into all the strains of the modern world and how it is basically set up to make us feel inadequate and worthless. But when I'm down, I never get to the place where I would want to end it because I have like a possibilities flow chart that is like my buffer between me and the bottom: There's always one last thing I would try or need to experience before I threw it all away.
What I mean is, even if you were penniless, odds are you could panhandle your way to some sunny beach somewhere and just watch the birds go by. You could go get some menial job somewhere beautiful and just live life day to day. Most of us never will. Some will tell you letting go of all the trappings of the modern world is the only way to really be happy, but even if you don't go that far, think of all the advantages you have to be living when you are: you have the internet at your fingertips, effectively you can learn or find out about anything you like. You could learn an instrument, become an artist, form a band, start collecting something, take up photography, meet new people, go someplace new, see new things, eat new food, experience a different place and change your perspective.
The lottery is a bad example, because odds are it won't happen, but what if it did? And even if you never win the lottery, what if you win a lottery of a different kind? What if you meet an amazing person/do an amazing thing/create something wonderful? Plenty of people luck into stuff all the time, be it money, relationships, experiences, or even happiness. You could be seconds away from something extraordinary happening.
Unless you have done cage diving with great white sharks in California, ziplined in Costa Rica, climbed Mayan pyramids in Mexico, surfed in Hawaii, snowboarded in Colorado, skied in Austria, eaten street food in Vietnam, meditated in Tibet, Hiked to the top of Mount Fuji in Japan, (I mean hell, put in your own ideas, I'm just spitballing here) and maybe most importantly, hung out with the loads and loads of poor but oddly often happy people in many parts of Asia, Africa, and the Americas.. then you have more to do.
If worst came to worst, go to plan B. Otherwise you'll never be able to say if life was worth it or not because you'll never have experienced it outside of your own little corner of the world.
ps - if you are some world-traveling beat poet who has somehow been everywhere and done everything, then I apologize for the suggestion. Either way, I concur with others who have mentioned that talking to a professional can't be a bad thing.