You should check Opensea, where most popular NFTs including Runis have a 5% fee which is charged on top of the 2.5% platform fee. Most people are paying 7.5% plus gas fees which is often a flat $10-12, which sometimes go to over $50 during periods of higher network activity. Despite these fees, Opensea has pulled billions in volume over its lifetime.
In terms of simply staying at 5% fee and giving 2% to burn, marketplaces will lose 40% of revenue which I don't believe is fair. With a 4/2 approach, everyone loses a little bit for the greater good of the ecosystem. This is all detailed in the proposal.
Yes, but no one is buying 1 cent NFTS on OpenSea, you are comparing two completely different worlds, and OpenSea is just a third-party to sell them. OpenSea is more comparable to Amazon charging a fee for people to sell their products on their platform. It comes with publicity, visibility. Third party markets in splinterlands don't offer extra visibility to the game, they exist because the game exists, they are used because the game gave them visibility. People won't find and use peakmonsters without knowing Splinterlands exists beforehand, while people will find and use OpenSea before certain NFT projects are listed there.
OpeanSea pulls billions of volume because it is the GO TO for any NFT investor/enthusiastic.