I'm just an old jobby hogger that never was any good at running, but I like it so I run. Not a HS or college runner. Started in my late 20's when I had ballooned from 150 in HS to 175lbs. Ran for many years at that weight, doing maybe 30-45 miles a week and sometimes running 2 or 3 marathons a year. I was totally one of those guys the OP posted about. Times were mostly in the low to mid 3's. I dunno ... it never occurred to me that I was even overweight. Who knows, maybe I just didn't want to face that fact.
I got semi-serious when I was 39 and dropped to about 165 and peaked at 62miles and ran a 2:58. Woohoo for me. In my late 40's, fatter'n ever, I started running with club runners and I noticed in pictures I looked like a gawdam Bulgarian weightlifter next to those guys. Disgusting. I went from 185 down to 147 in about 2 1/2 years by cutting sugar and carbs. PR'd every single distance in my early to mid-50's. I've backslid a little to 155 now but I'm still within spitting distance of HS weight at 57 years old. I will never go back to those fatass days. Can't believe I allowed myself to get that way. Now that spring is coming I'll push to get back under 150. I seem to pack a few pounds on in the winter.