It can be a fun for them if they know how to control themselves, have discipline and know how to stop if you need too. On the other hand, it can be a threat for the gambler if they don't know how and when to stop especially if they are losing too much money.
For me, instead of deciding if gambling is a threat or fun it would be better to just stop gambling at all .
Being a person we all have different perspective in life. Yes agree it depends upon the person if it will be threat or fun for him / her . Why stick to gambling when it is not beneficial at all ? Gambling does not require us to put all of what we have. Instead,put all what we can afford to lose and do not be so greedy. It is not bad to play. The thing is, do not be so greedy.
That's human nature, being greedy when opportunity knocks in. It is easy to say but once you are eaten by the system, it is hard to get out. So before things get nasty, you need to decide for yourself which path will you take. The fun or the threat? It all depends on you because no one else will help you but yourself.