Cracking your back too often or in excess can be bad for your back and could lead to back problems.
But cracking your back in moderation when needed can help your back problems and can help to relieve pressure in your spine.
If you crack your back too often then it can lead to excessive wear on your joints in your back and then cause them to breakdown prematurely.
If that happens then you could become disabled as a result of excess back cracking.
So only do the back cracking in moderation and when needed to prevent any spine damage which can lead you to not being able to move or lead to you being in more pain.
Also be sure you know how to properly crack your back as it can be damaging if done incorrectly.