I got the answer for you Brian .... Cause they are much cheaper than cars!!!! I'm on Mustang # 10, and I used to have 3 at a time (2 68 GTs, and a 70 Boss) all fastbacks w/4 speeds.
But the chainsaws don't need insurance, registration, annual inspections, or much garage space, they are perfect!
Now, the other reason for many ... Well, we need different sizes for different things, and then a backup, and then a backup for the backup, and .....
OK - IT IS A DAMN ADDICTION - IT IS CAD - END OF STORY!!!!