Pretty much similar to your situation, even though I am rather a casual bettor and do not bet in many sports. Those are the kind of situations you need to be ready for when you become a gambler, one needs to learn how to face disappointment and be ready to the worst case scenario.
I believe there is where you failed a bit, in both occasions you decided to go all or nothing and not settling some something in the middle.

Perhaps that is where we all need to start to learn some lessons from... Those early multipliers you were being offered by the casinos were already extremely high when compared to any investment out there, so why not take it? because we feel would be missing out even more money? It is the same sentiment which makes people not to sell their trading positions when it is pretty obvious they are riding a bubble which is about to burst.
... Heh, we human beings are probably the only sentient creature that stumbles on the same rock money than once.