In my opinion I guess a gambling site would be always more profitable.

If someone starts being addicted to it, the amount of money they can throw in to just try to win all the lost money back is absurd. People sometimes just don't know how to stop and that will probably enrich someone, but not the user himself.

I am programmer myself and if I had time and the market was not totally saturated, that would be probably something I would go with. However trying to offer something totally different from what currently exists.