Ebay Fees take 80% of Seller Profits

Is it fair to say that eBay is taking the profits? Or have they just created an efficient marketplace with such a low barrier to entry for both the seller and the buyer that profit margins are getting pushed smaller and smaller.

If eBay cut their fees in half, wouldn't sellers lower their prices to compete against each other?

I think this is the natural consequence of efficient consumerism where the sellers offer no valuable differentiation of service. I appreciate it when I get fast shipment, and maybe some free candy included with my purchase, but that hasn't yet inspired any 'brand-loyalty'.

On the plus side, I think this helps build a market for sites like Etsy where there's a clear scarcity of merchandise.