Why would anyone place it vertically?

My friend Robert had his vertically place but his cat "Magus" came can knocked it over, the PS2 hit the floor and the disc tray lid opened when it hit floor, the disc for Devil May Cry was lodged in there, he had to open up his PS2 to take the disc out but the disc was so scratched that he can't play it anymore, he went to get it resurfaced.