First, it sounds like you're probably having a quarter life crisis. Comparing yourself to others never helps and I guarantee that all of those people accomplishing things aren't nearly as settled or secure as they seem. You've beaten cancer and graduated from college, so already you've shown a tremendous amount of strength, will and determination.

If you really can't find a job and aren't sure what to do, I would suggest trying contract/temporary work. It may suck, but it could give you a taste of some various types of jobs and spark an interest you didn't know you had. You could also look into doing some volunteer work, maybe something related to cancer patients since you've been through it. Sometimes when life sucks, helping other people really does help shift your perspective.

Lastly, some things I wish I knew at your age.
1. Your life really is in your hands. You control how you react to things, you can and should cut out negative people from your life, and building anything is all about taking tiny steps.
2. Being uncomfortable is a blessing. It means that something isn't right and the best way to fix that is to try new things. Meet new people, try new hobbies, try different perspectives. For me, googling
any thought or emotion that comes into my head has opened my eyes to whole new worlds.
3. Don't worry about other people. I guarantee that most people are way too wrapped up in their own lives to be hyper focused on yours, so just live and don't be afraid to fail. Failure can actually teach you way more about yourself than succeeding.
4. If all else fails, just focus on what you do have and what you love. A pet, a family member, a friend, a book, a movie, a place. Just stop and appreciate it.