I am also think with the same way that gamble isn't any bad think. Yes it's convert to bad when one person got addicted on it . I think not just gambling but over-indulgence has a bad effect on everything. So in this way gamble should be in self control and also it's purpose should be only entertainment which already mentioned by op.
As long as we don't use gambling to make money and keep trying to control ourselves, I think gambling is fine and we can even enjoy it as entertainment. But indeed, many people have lost control while playing gambling and we have seen it. Many of us have experienced it ourselves and want to learn to control ourselves before we experience a serious addiction to gambling. By making gambling a form of entertainment, we must know the consequences, especially if we have often used money and time to gamble and do not let us get addicted.