When you upgrade to NFTizer multi-chain you will gain the ability to deploy NFT minting contracts also on 5 more blockchains: Polygon, Avalanche, Binace Smart Chain, Fantom, and Harmony.
Since every blockchain has its own raving fans who prefer those blockchains over Ethereum, by upgrading to NFTizer multi-chain you gain access to a huge number of new buyers.
You can think about those additional blockchains as new markets you are getting access to, which boosts the number of prospects for your NFTs