There are four kinds of competitive advantages.
1) Proprietary technology(Microsoft)
2) captive customers(Coca, Microsoft)
3) economy of scale with some captive customer(Walmart)
4) special resources such as regulations.
in that sense, Dell really does not have a competitive advantage. Take a look at Dell's profit margin. It has been going down every year. If I were Michael Dell, I would start a trust fund and donate all Dell's shares to the fund. then I will slowly sell shares in the name of the trust fund and investing the proceeds to Coca or Microsoft.
