I don't gamble - although like you I may have had the odd flutter in the past on a special occasion - but it was one offs. I haven't done it once for years now.
I don't really have too much short term debt. I just have my long term debt on my mortgage which is luckily capped. I use short term credit for company expenses but they are pretty good at paying back within 2 weeks and well within the payments terms for starting to pay interest.
However, I see people around me getting into impossible debt loops where they are using further credit to pay off bad debt. Is it a lack of education? I think it is largely desperation because people are backed into a corner. They may have overspent when credit was too cheap and are now paying the price.
You have to see credit as borrowing from your future self. Are you going to be happy in the future when you find you already have spent the money you are earning before it even hits your pocket?
RE: Interest irresponsibility