Are all men bad with money? How can I get my fiance to handle his finances better?

I've just realized that i've never met a man who can manage his finances. My sister agrees, my mom agrees, my friends agree- has anyone else noticed this? Every man I know wastes money on 'toys' and other frivilous things- is in debt, just can't manage money and save. My finace has a 12,000 dollar debt and I don't want to be a part of it. I don't want to marry into that debt. I hate to lecture him about money but even tho he says 'I know, I know, stop nagging me, I know how to manage my money' he still makes outrageously unwise purchases, wastes money on beer at the pub, cigarettes, buys me presents he can't afford....I'm at a loss of what to do. I just want a responsable money savy man. Will I ever be able to help him mend his ways???