Future-proofing your business is great, but if you can't hold on long enough to even exist in the future, then it's premature optimization.
2. If he does not take plastic, then people who only pay with plastic are not his customers. Their needs are consequently irrelevant.
3. the $.25 donut is a loss-leader to sell the $4 cup of coffee. Or you could look at it as a bonus of sorts. Compare: "Buy a $4.25 cup of coffee" with "Buy a $4.25 cup of coffee, get a free donut."
4. It's generally an (illegal, yet surprisingly common) way to avoid taxes.
In terms of baked goods, they weren't low quality, they were just home baked. John used to work with a local bakery, but no one particularly cared to get their slightly above average quality.
The whole point of the article is that your intuitions about what is true or false is unreliable. Instead it is better to experiment with different options and measure the results. Choose the best option based on real data rather than unreliable intuitions.
Article says it all really. Don't assume.
They were homemade for Stallman's sake!