You should not convince people that gambling will be a quick way to make a fast buck. Gambling is profitable only in sports where you can get a slight edge over the bookmakers. In casino gambling, you will most likely lose your money in the long run so if you wants to introduce gambling to someone, you need to warn him/her on the risk he/she is facing.
In sportsbetting, there's no assurance that you are able to make it there. But for experience ones, I've seen that its really profitable so I guess I'll say that its no guarantee to the newly sportsbettors.
Warning the person you introduced in gambling should be oriented on what are the closest effect that will happen.
It's good to follow some of the sports that you know, like know by heart. You could never be sure with what would happen, but you have an advantage over the knowledge of the teams in sports. It's either you accept that or not. It's hard to influence someone that hasn't experienced anything close to gambling; you might start his or her addiction.