My own self-esteem varies from very high to very low, depending on a number of factors. It's generally higher these days, though, than it was a few years ago. This is generally because those with higher self-esteem didn't look down on me, but focussed on my strengths and encouraged me to recognise them and develop them.
If I find myself with under-confident people then I really do try to treat them in the same way as I've been treated of late. I've found that if you take the time to find and recognise their talents and strengths, they often turn out to be amazing, wonderful people to know.
My advice to you, angryman, is to find yourself a new hobby, maybe something social - and I don't mean clubbing. For me, it was learning an instrument and joining a band, but you could take up a sport or join a class or something. Just get yourself immersed in the activity and the social side will develop. Yes, you may find yourself chatting with people with people you wouldn't look at twice in the street, but it's a wonderful feeling when, after a week or two, someone casually strolls over to you and asks what sort of week you've had, or how you're getting on with some aspect of the activity or whatever.