They make plenty of left handed trackballs for a reason: Left handers are naturally 15% more intelligent than right handers are and many wind up as engineers using cad programs where the track ball is an indispensable tool.
The gaming industry simply assumes that left handers don't game for that same reason.
Truth be told, I'm ambidextrous. I can use either hand but prefer my left. John was strictly left handed. He couldn't do a thing with his right. I golf right handed and throw right handed but bat left handed and kick with my left leg. (Not that I do any of that anymore with my back issues, but there it is.)
As you should know by now, I'm a pretty messed up individual.