My company does Machine Learning for Sales. There aren't a huge number of people who can do both programming and statistics well. Add Sales to that skillset and there are, what, 5 people in the world who can do all 3? The odds of finding a sales person who wants a predictive sales tool and has the capability and interest to write it are vanishingly small.

For a consumer-oriented example look at Coursera or other MOOCs. Andrew Ng is not a Coursera user (i.e. student.) He understands students, and that's enough-MOOCs provides enormous value because they solve an important problem. Students would have had a much harder time creating Coursera than Ng.

I as well. Most software sucks because the people building it aren't motivated. Building for oneself is one source of motivation, but it's myopic to assume that it's the only source of motivation that works.

It seems to me it isn't saying that casinos are like software development, but pointing out human psycology using the casino as an example.

The same reward system is there because the psycology (human) is the same.

TLDR; If I compared the performance of the same car on a road to a dirt track, I'm making a comparison, but not a metaphorical one.

He's comparing gambling (e.g. risk-seeking) with software development practices that are more often than not an incompetent expression of risk-aversion.