A number of reasons, of which I will count the best I can:
1) I was brought up around firearms. My greatest hero, my Dad, always had several on hand. He introduced me to them and taught me how to handle them safely by the time I was 6. Guns were as much of a part of my early life as pillows, pop tarts, and Capt. Kangaroo.
2) I hunted extensively as a youth, and yes unescorted from the age of 10. I know, I know, different times back then. Just trying to tell you where I'm coming from.
3) As an LEO from 1979 to 1995, I relied upon firearms for my personal defense and the defense of my LEO brothers, not to mention most importantly my family. When I left Law Enforcement and moved to Panama City in '95, we met upon hard times after about a year, and eventually I had to sacrifice all but 2 of my firearms just to keep food on the table. The only two that I kept could hardly be classified as SD weapons. A 1906 Winchester .22 pump break down carbine that my Dad bought me when I was 6, and a very old .32 cal. rolling block squirrel rifle (make unknown to this day) that belonged to my Grandfather. Thankfully, the hard times succeeded before I had to bow to the pawn shop with either of those two. I've always regretted having to pawn some of my favorite possessions, but I did so for good reasons. I vowed that whenever the crunch eased, I would replace my firearms the best I could without hurting my family's stability. I'm finally able to do so. I'm not making an arsenal, just buying what I think I may need for realistic scenarios. I rarely hunt anymore, so high powered hunting rifles with tons of camouflage have little appeal to me.
4) The older I get, and the less able and willing I am to physically confront a BG (believe me, in my earlier days, I used to LOVE whoopin' someone's arse) the more that I returned to relying on my firearms training for protecting myself and my family. That said, since I am older, my training, reflexes, and shooting ability are not what they were 15 years ago. That's why I'm hitting the range more often now, joining up for IDPA matches, and wanting to attend the next "Brownie" weekend when it is offered on a month that I can attend. I was as bad arse macho as you could get 17 years ago in my prime, but I'm not in my prime anymore. I'm not too big of a man to realize I need help and practice to get back to where I need to be.
5) Obama. Need I say more?