Honestly, it's probably harmless.
There's alot of articles about this, explaining what's actually happening when you do that (as I understand it, it's a bit different from what people think is happening), and the idea of it being constantly damaging seems to be a myth.
Me, I've been doing it for as long as I can remember. I can crack my toes as well (which bugs people more, because instead of "crack!" it's more like "CRUUUUUUNCH"). I'm actually very prone to things like joint problems or tendon/nerve issues, too. I have problems of varying sorts, including even a bit of arthritis (not in my hands/wrists) in a couple of places (and I'm WAY too young to have that). And I do things with my hands ALOT, since my main hobbies are video games and other computer-related stuffs. But even despite all that... my hands have no issues. I dont get pain there usually. The only time I DO get pain there, it's "referred pain", which is actually coming from somewhere totally different; I go to physical therapy for this. It involves them working on my neck/shoulder.