Licensing. They were the first ones to believe that they could make real money selling O/S and software, rather than just hardware.
Digital Research beat them with CP/M on the OS front for microcomputers. The company that
wrote DOS (a CP/M clone alledgedly) obviously beat them (MS) as well. I don't know if anyone beat them for BASIC though.
A company called MicroPro was founded to sell a word processor (it became WordStar) in 1976, long before Microsoft developed Word..