Many small stake pools struggle with increasing their stake. The stake could be increased by adding the value of all the NFTS held in wallets by both delegators and operators. How do we determine value? Once we have smart contracts, value will be the last sold price of the NFT, recorded in the Blockchain.
If the value of NFTs (their purchase price or last traded value) were to be added to staking then both the ADA used to purchase them and the NFT would counted. This would make it possible to double your staking rewards by selling an NFT to yourself or a collaborator.
It would also affect the Cardano monetary policy.
Stake pool operation is a serious undertaking and gathering enough stake to establish a viable pool is part of that challenge.