He had already gotten a masters at MIT and a phd from Stanford. From his Wikipedia:
During his 25-year career (1958–1983) at Texas Instruments, he rose up in the ranks to become the group vice president responsible for TI's worldwide semiconductor business.[13] In the late 1970s, when TI's focus turned to calculators, digital watches and home computers, Chang felt like his career focused on semiconductors was at a dead end at TI.[2]
Chang left TI and later became president and chief operating officer of General Instrument Corporation (1984–1985).[14]
So he was already running massive companies by that point anyway haha