Amazon leads the market for many reasons among those price, selection [1], reviews, and then with more recent shifts faster shipping. The goal isn't to beat Amazon the marketplace. The goal is to bring the Prime experience to other marketplaces. I don't believe it's a zero sum game.
Amazon is a lot more comfortable than they were 10 years ago, and you can already see that as a result in higher prices [1][2] and lower shipping SLAs. Lifting the rest of the market increases competition and helps all buyers have a better experience.