Because those could very well happen to you tomorrow on that ride.
1)I have never broke a deraillieur before.
2)I have not had a flat in well over two years <--Worst one.
3)I am on a hot streak I won't crash.
4)The chain won't break has not broke after the past year and a half.
5)Clipless pedals are easy.
6)I have a bunch of miles in, I won't bonk.
7)I am feeling great, no chance of me being sick in the morning.
8)My frame is tough it won't break.
9)I don't need a pump since I don't flat.
10)There is never huge amounts of obstacles on the selected route.