The problem is you're not having to rush to the store and buy it. You jump on the computer or easier still get your phone out and make a bet.
And for anyone who bets on sport, if you're watching the adverts at half-time and Ray Winstone offers odds on so-and-so to score next, you think about it for a second and decide not to bother, and then it happens in the second half, you're kicking yourself for not making the bet and it just makes it all the more tempting the next time. In other words, even if you don't act on the commercial, you're then hoping the thing you didn't bet on doesn't happen in the 2nd half, so it still ruins your enjoyment.
There was supposed to be a ban on advertising during the game so maybe those half-time adverts don't happen any more, i'm not sure (i lost all interest in soccer after project restart) but even if that rule has been enforced, they'll still get round it by advertising immediately before the game. Enough clubs are sponsored by gambling companies etc