But he's human - we all are and that message WAS the message sent.
A lot
of people in this world would be consumed by such an item! Perhaps it seems entirely illogical to you, but it's actually very realistic. What if something like that was at your fingertips? Sure, you could say 'I would never do that, I know myself," but have you seen the people in this world? I'm not saying you would go the route Sanders did, but there are a LOT who would. Mike (?) showed us just how quickly a human could go from being so satisfied with life, to getting greedy and selfish and consumed with this amazing remote. Look at lottery winners! I'll bet you over half of them are completely and utterly satisfied with their lives before they win. But look how messed up some of their lives become? They become consumed with their money, forget about their old life and drown in the potential new possibilities. Well? Sanders won //his// lottery in this movie. He got a remote and got greedy. This movie is entirely realistic and sends a pretty good message in the long run.
So yes, I think the message is, "Appreciate what you have" and also "You don't know what you've got until it's gone." Because we are creatures that truly don't understand that.

Except that's the way some people are in life, they don't stop and evaluate the way they act at certain times and instead just repeat the same behavior every single time they're put back in that situation without even stopping to think about it. It forced him to look at how he acted and what he had to do to fix that.