>such as whether you have anyone to support you
Partly this, but it's more about motivation. Support is only good to give you a boost, get you the connections you need to make it - you have to do the rest on your own. Have goals, take the initiative, keep your nose to the grindstone and all that. That's what's really necessary for success.
I used to have a serious motivation problem. I now have a lot more than I used to as a result of increased caffeine use and a desire to make money and move out. However, I don't have any goals.
If you think about it, there are only two "normal" goals people work towards in life: entering and succeeding in a certain career path and having a family (everything else, like owning a car, a house, etc. are just consequences of these.) There's no particular career I want to go into. I really don't care what kind of job I work as long as I get enough free time to pursue the things I enjoy. And naturally, having a marriage or a family is out of the question, so that's not something I have to work towards.
I'm still happy to be working, though. I've found that I enjoy working, because when I work I'm not thinking about what a piece of shit I am - I have to concentrate on my job instead. It's something to consider. If you're intelligent, I'm sure there are some skills you have that you can offer to a potential employer; you just have to know how to "package" yourself. Hell, even if you're average. I don't think I'm that smart.