No, nobody's trying to argue that gambling is
by definition bad – that is to say, nobody's defining the category boundaries of "gambling" contingent on possessing the property "is bad". Some people have constrained the definition of "gambling" such that it only contains things they view as bad, and then observed that all the things they consider "gambling" are bad, but that's not the vacuous, circular claim you make it out to be.
In lieu of re-quoting other parts of the thread, I'll instead ask you to please re-read the arguments people have made, more slowly.