Wintertime seasonal affective disorder (aka SAD) can be a dangerous thing for some people. Symptoms include depression, anxiety, and the near-suicidal urge to ride an inner tube on icy public roads while being pulled behind someone who's driving way too fast.
It's one thing to risk your life like our rollerblader behind the motorcycle last week; at least he could steer. Radical extreme tuber dude up top may be able to squeeze out a little directional foot-friction control, but mainly he's just hanging on for a fast, cold, freakishly dangerous ride in a blurry world full of trees and cars and other very solid things. Thrilling? Hell, yes. Smart? About as much as playing tennis with a hand grenade.