system
A chat on subreddit /r/pcmasterrace
human
It's easier to learn to use computers right handed than to be stuck buying specific gear or be uncomfortable at other setups.
gpt
For me when I got into gaming as a kid I played games that by default had controls on WASD and the arrow keys so as a lefty I just grabbed the mouse on my left and started playing with the arrow keys. As I got into more games I started being really limited by the arrow keys awkward position and the lack of surrounding buttons but I had already gotten used to holding the mouse on the left so I switched to IJKL. It works great for me, I don't feel like I'm in a disadvantage at all, just means I have to rebind all my keys in every game and I have to buy symmetrical mice with side buttons on both sides.