I keep 2 on my truck. I go through periods where I never use them. I go through periods where it seems I can't stop using them. Mostly the abrasive cutoff disc they make. You can do some damage with one of those.
The barrel shaped sander is great to clean soap and rust off Direct Drive motor shafts.
When phillips head screws get rusty and won't turn or strip out I cut a slot and use a flat screwdriver.
Cutting seized bearings on commercial laundry machines, and the list goes on.