Why do Pros TILT their keyboard?

Introduction

How do people play like this? It feels so bad! There are some pros out there, or as I like to call them, sick freaks, who tilt their keyboards to a certain degree that is quite frankly obscene. To a more untrained eye, this looks ridiculous and painful, but apparently, some people swear by tilted keyboard setups.

For example, when I play like this, I have much more control. I know that a lot of people use their keyboards horizontally, but I see that as a disadvantage. I can reach a lot more keys easier, in my opinion, if I have my keyboard vertically. With my thumb, I can reach all the way down to the end of my keyboard.

I don't know about you guys, but maybe there is something to this. However, let's be real here: no matter how comfortable you are, turning your keyboard upside down to play is still cursed. Someone's keyboard was upside down, and my reaction was, "My god, dude, what the..."