I bought a TRS-80 computer in 1977 to help me do some heat transfer calculations for the industrial heat exchangers I was selling. It gave me a big sales edge, and I offered a free tape to others selling the same stuff in other parts of the country.

But they couldn't use their computers! I realized that I had skills others lack, so in 1983 I started my computer consulting business.. and closed it in 2016 :)