Contests can provide a fun incentive to any interested topic but ultimately it breaks down to value. There has to be perceived value in the giveaway and the interation between the audience and the contest provider.

The best contests add value to the community (in this case Steem Monsters by providing art, music, story and also helping users increase their card count! :)

The secondary hope is that by holding contests more people might be inclined to do similar - in turn it may increase the reach the 'product' has on the wider audience. If only everyones grandma can start collecting the cards then its a success. :)

Many thanks for the contest! :)