I agree. I happen to sell the same things on my (pretty good!) Shopify store as well as on Amazon. Amazon outsells about 2000:1. The reason why is simple -- it's traffic. If you can get traffic on your own, say with a giant social following or TV presence, then owning your platform probably does make sense. Otherwise go to where your customers are. It's like the old retailers' saying: "Location, Location, Location."