Try and find the book "Programmers at work" by Susan Lammers, subtitled "interviews with 19 programmers who shaped the software industry" (slight hyperbole), written in 1986. Apart from the value of the interviews themselves, it is fascinating to read them 35 years on to see how much has changed.
One of the interviews is with C. Wayne Ratcliff, who "In 1978, began writing the Vulcan program, which he marketed by himself from 1979 to 1980. In late 1980 he entered into a marketing agreement with Ashton-Tate and renamed the Vulcan product dBASE H." It looks like Vulcan was a success because it was a good product and didn't have much competition at the time.
RATCLIFF: In October 1979, I went to market and put my first ad for
Vulcan in BYTE magazine, and I ran a quarter-page ad for four or five
months thereafter. I got much more response than I could handle.
INTERVIEWER: So your response was immediately positive. Who were your
competitors at that time?
RATCLIFF: FMS 80, and later Condor and
Selector. During the year and nine months that I was writing the code
for Vulcan, my floppy disk drive broke down twice. Each time, it took
three months to get it up and running again, so I lost six months. I
kept thinking, if I had come out six months earlier, I would have been
the very first.
INTERVIEWER: So, suddenly you had a product that was
penetrating the market. Did this success take you by surprise?
RATCLIFF: I got completely overstressed. I did everything myself. When
an order came in, I typed out the order, filled out the invoice,
packaged the program, made a fresh copy of the disk - the whole nine
yards. I placed all the ads myself, and also I kept working on the
program. I'd come home from my job, work again until midnight, go to
sleep exhausted, get up the next day, and repeat the process. Vulcan
was at the point where I needed to make a lot of advances to it. Over
the months I really ran out of steam. In the summer of 1980, I decided
to quit advertising Vulcan and let it drop off to nothing. I would
continue to support all the people who had purchased it, but I wasn't
going to aggressively go out to find any new buyers.