I don't think they are, why would you have to hold the glass for it to move around? I still wouldn't use one though, i mean, it may be used for ghosts but there might be other entities what are dangerous.

Many studies have shown that Ouija boards work because the people using it want it to work.
Subconscious thoughts can manifest themselves in movement, the person might not even be aware that they are moving their hand, but they are.
It's the same reason as why Voodoo seems to work.
If the person truly believes that it is going to work, their subconscious manifests the effects with pain, or restraint, depending on what is being done to them.

I dont know ive been to scared to touch one... haha

Myself and my mother have done one of these, I didn't want to do it and had a friend, my friend knew all what was going on and it was just messing with my mind, but they knew all the answers, I don't believe it

I dought it i think the people just plan it out.

I believe 50/50 because sometimes people just move it to pretend and I also believe in spirits and such so it might also be real

Honestly, I think they arent. I dont believe in all that ghosts ans sprit stuff

The only way to know for sure Is to try It yourself but I don't recommend It

ive used one several times, told it to possess me, annoyed it, threw it to the floor and just left it there.. Its all bullsh*t, no, i didnt get possessed and no, it didnt magically disappear..
Its you who is moving it.. its sold in kids toy stores for christ sake..