Wasted life? I'm not sure that you can qualify any life being wasted. Life is for living, and if you live in hatred of yourself and all that you have become, how is that any less of a life?
Rather perversely I find that I'm most comfortable when I'm miserable. Whether or not that's because it's just easy or familiar is something I leave up to you to decide.
How I've spent the last 10 years of my, relatively short and relatively eventless, life? Wallowing. Dedication to self improvement in my knowledge of computer systems and networks. The battle of lack of self confidence. The death of both my parents, and dealing thereafter. Several years of teaching myself that non-socially acceptable ways of dealing with my personal life experiences is perfectly fine and everyone else can piss off. Realising it's ok to be silly from time to time (that's a newish one).
My life has been no different from others, less eventful than others and more so than some. Whether or not you've wasted it is a matter of perspective. Two years ago I would've said that I've wasted what I've had. Now I'd say I haven't.
The simple thing is that I've realised is that it's irrelevant. Something I have planned to get tattooed on me is a nebula and star field scene, and then several golden ratio sprials cut in over the top. The simple reason for this is that every time I look up there or think of the golden ratio it reminds me that it's completely pointless. **** everyone else. If you're happy then it's fine. If you're not then change it. It's never too late to change, if you want to. Whilst I'm happy being miserable and the lack of importance is comforting to me, it may not be to others.
Everyone touches someone else, in some way, shape or form. I can name several individuals who I've met and some who I've only conversed with on these very forums who I feel have changed my life. Whilst they may feel that what they've done is not worthwhile I'd argue that by affecting one person they have made a worthwhile contribution. To those many people, I salute and thank you all.
So I'll reiterate; Wasting life is not possible. Whether or not you're happy with your decisions is a matter of your own perspective. But remember the simple fact; You cannot change the past, no matter how much you want to. Sometimes making a mistake can result in some of the greatest clarity in life, that you may not have otherwise gained.