46 days and counting

So here's my question:

If I can swim 2.4 miles in 1:30:00 and I've ridden 112 miles sub 6:00:00 more times than I can count and it seems like I can maintain a 10 minute mile pace forever (this is a 4:20:00 marathon) why in the world won't I do a sub 12:00:00 Ironman?

None of those times individually is particularly impressive. In fact the 1:30 swim is pretty f-ing slow but if you look at the results from last year a 12:00 race puts me 94th out of 354 entrants in my age group and 459 out of the 1944 total entrants.

I guess I'll answer that question myself either way in 46 days.