I think Amazon has one major advantage over Walmart: they don't care about profits and generally run things at break even. This in itself is super powerful, b/c

I think Amazon has one major advantage over Walmart: they don't care about profits and generally run things at break even. This in itself is super powerful, b/c Amazon investors can take their profits by selling the stock (e.g. capital gains) whereas Walmart needs to pay dividends from profits. A decline in profit will lead to a significant hit in the stock price for Walmart.