It's exactly because I don't have to think about everything by myself, I'm completely happy using somebody else's well-maintained library and adding it in. It saves time, mine and everyone else's, and frees it up to do other things. "I guess if you have to work on team" - wait you never work with other people? I think that's kinda the basic requirement for many software projects that they scale outside one person coding in a basement or cafeteria.
It's just that if nobody except you can understand the patterns you've created the code is not very maintainable in the long run. Sure it's probably fast and slick, but when you're gone can the next guy read your code? And more importantly, build on top of it?