The first step

OK, so I have a problem.
It started fairly innocently really. I was at my aunt's funeral a couple of years ago and dad gave me $50 to have a few bets on the horses.
After looking over the race fields I decided to head to the poker machine (or slot machine for anyone in the USA) area and spend it there. Guess what? I ended up with about $150.
They don't call it beginner's luck for nothing.
Technically, I wasn't a beginner. When I turned 18 I decided it was something of a rite of passage if I played the machines - so I invested $20 and played for a while and wound up collecting $20. Harmless, really.
Somehow after that experience in Orange I started to play the machines a bit more. I'd put in $20 here or there. Again, harmless fun if I lost.
Over time it grew to putting in $50 at the start and increasing the wager. I've never gone higher than that as a starting point but quite often I haven't stopped at that initial outlay.
Somewhere in the human brain is a switch that seems to stop the common sense part of your mind and allows you to think that you can win your money back and then some. Even though you know that at best it comes down to random luck and at worst it is geared towards you losing, you still think that.
I don't know how else to explain it. I know you can't win in the long run. The short term you can get some wins but you're kidding yourself if you think it can be sustained.
Out of nothing this habit has become a problem. I vow that it won't have any further negative effect on me, it's not fun and I can see that it has the potential to grow into a bigger problem.
Why bet on pure chance with a machine when it is designed for you to lose? I've spent most of my professional life working in the horse racing industry and I know all about risk. With the horses there are factors that can eliminate certain outcomes, with the machines you have no control - it's all down to pure chance and, as they say in casinos, the house always wins.
So I have taken the first step - this is a problem that can be fixed.
Stick with what you know and back yourself, not a machine.
I must be strong in keeping myself in line and then what has become a bad habit can return to something that I tried once and moved on, once again.
Why is it, though, that a habit (particularly a bad one) is so easy to start but so difficult to finish?