OpenSea is one of the popular NFT marketplaces that creates a lot of attention to many fintech entrepreneurs. But, in the initial stage, they earned just $251/per month. Within a year, their monthly fee exceeds $50K. In 2020, their total profit raises to $100K. Finally, 2021, was one of the best years for OpenSea, because the NFT sales and their trade volume hit an all-time high and reached...