A person should be very careful in cracking their own back. I have seen many injuries from people trying to twist themselves into a pretzel to relieve pain. I have also seen many people injured from other people who “saw a chiropractor do it on YouTube” so they are now Doctors of Chiropractic and go around popping/ cracking their friends’ backs. Cracking your back has nothing to do with an actual adjustment! A proper adjustment specifically finds the subluxation/ misalignment (harder than actually adjusting it), applies the exactly-appropriate technique in the precise line of drive to correct it and uses just the amount of force necessary.
I’ve seen some pretty amazing snowboarders on YouTube with Red Bull helmets on going down crazy-steep slopes, jump off 100-foot cliffs, and do 4 flips in the air with 6 twists. Or I’ve watched Bob Ross paint landscapes that are stunningly beautiful and make it look so easy! That doesn’t mean I can do it.