Interesting. Looks like people of all age groups who actually carry a defensive weapon because they think their life might depend on it sometime tend to favor the most modern, reliable, high magazine capacity handgun they can get.
I'm in the 21-29 group and carry a revolver, but I still think this is a fair generalization.
A big inhibitor for me is simply cash. As a young family man with 3 small children and a mortgage, financial constraints are a significant factor. I've chosen to carry that which I am in a position to practice with regularly. I'm tooled and well-stocked to reload .38 specials/.357 magnum, as well as .45 Colt greatly due to having a dad and grandfather who have been shooting these for years. I split the cost of bullets, powder, and primers with my dad (brass isn't an issue), and I use his reloading equipment.
I'm not tooled to handload 9mm or .45 ACP. I would need to purchase new dies. The alternative is to practice with factory ammo - which is obviously more expensive. At best, you're looking at what, $0.30 per round with FMJ .45 ACP, and maybe $0.20 per round for 9mm? Even if that's slightly off, I can do
much better than that shooting lead handloads in my revolvers. Aside from that, buying a new automatic also necessitates the purchase of new accessories (magazines, holster, mag-pouch, etc).
I'd love to get back into the 1911 business (I've owned 2 Springfields since I've been married and ended up selling both due to a few tight financial months), but I've accepted that it will be a few years before I can get there.
I think many will agree that carrying something you can afford to practice regularly with is of great importance.