If game is popular the price of their NFT will continue to grow because it will be a lot of gamers who want to buy such NFT.
It is very important to create the demand in NFT that their price will continue to grow in future.
I agree that now the popularity of NFT continues to raise. People buy NFT because they believe in their future growth.
But what it will be when the price of NFT will stop to raise and will begin to fall? People will stop buying NFT and start to sell theim.