First, let's state the obvious:
1. A primer costs less than two cents; and
2. There is a theoretical, even remote, chance of detonation
if you deprime a live primer.
With that caveat, let me state that I have deprimed many live cases and NEVER had one go off. Then again, I don't slam the lever down and ram the decapping pin into the primer. I may be cheap, but I'm not [that] stupid!
Also, my presses will simply aim the primer down into a collection cup should it actually detonate. Lots of open space away from any powder for the flash, too.
Heck, I've reloaded the primer with no ill effect. The reason for the deprime was the occasional crunched case when it got caught by the edge of the bell-mouthing die.
I just like getting 100 cartridges from 100 primers (1 tray).
Your eyes, your choice.