Does anyone know why nfts are so small?

Because storage space on “The Blockchain” is very expensive.

The blockchain is a complete list of all transaction made with a cryptocurrency. You have heard of miners. What they do is collect transactions and append them to the blockchain. Every miner must have a complete copy of the whole chain. So whenever a new NFT is created, lots of copies have to be stored and kept forever. It’s just not a good solution from an engineering standpoint. But for the popular currencies, that’s the smaller problem.

Every miner wants a fee for their services. That fee depends on the value of the cryptocurrency. There is no relation to the actual storage cost.

Besides, crypto does not offer any kind of DRM. If it did, the copyright industry would be all over it. Anyone can download anything on the blockchain.

The reason you can’t resell games is, because the publishers don’t allow it. For example, Steam has a marketplace. It would be no technical problem to make games transferrable between users. The rights-owners don’t want that.