It's pointless arguing with them.
This is not gambling. It's no different than a retailer giving you something free, hoping that you keep spending more. If this is gambling then so is switching banks or utilities to get the cash offer.
I agree gambling is a mugs game. If you can't lose though you can't call it gambling. I've given up trying to explain the concept. Most can't get their heads around laying a bet and look at you like you're mad.
Both teams to score first half is my bet. Select bet 'no' before the game and then 'yes' inplay. Decent returns and comes in quite often, including Juve v Sp*rs last week. Used to get £50 on both mine and my girlfriends account (which she knows nothing about) but only get £10 now, still cant complain its better than nothing. Also worth noting thats its best placing the inplay bet IMMEDIATELY! Juve proved that last week!