Ultimately I agree with part of this statement.
You need to differentiate “problem” gambler from a gambler in general.
Plenty of posters here for example who expiry the point. You can be a gambler and not be a complete degenerate - they keep gambling money apart from their other money - recognize that gambling is not a “sure thing”, don’t get in over there head or let gambling spill over and take control of other areas of their lives.
Then there are the degenerates (and we have a few of them posting too) - they can’t manage money, they would do any and everything to score a few dollars to play on a “sure thing parlay” tonight and are simply untrustworthy addicts.
Sadly - it can be difficult to confirm someone has crossed over to the dark side. Similar to booze - some people start off fine and slip out of control and hide it well for a while. Sometimes the temptation is just too great - sometimes things happen in life and gambling becomes a release from reality. Whatever it is - it’s a dark place to slip into and you’re correct - you cannot trust someone when they have crossed over to this spot (be it gambling, booze, drugs, whatever).