Sure, if you are happy paying the higher monthly premium to cover the reduced handset cost in the first place... Then of course you need to get yourself another phone to use, so I fail to see how you think that is considered making a profit. The fact is, just like with cars, phones only ever end up costing you money, and just like with cars, the cheapest way to own one is to keep it for a very long time until it becomes false economy to keep it going, or it gives up on you and needs replacing.
It's crazy how people think they are making a profit or cheating the system by adopting various contracts, then selling, then buying outright, then selling, then going back on a contract etc.