> Then Apple finally released the iPhone mini and nobody was buying it, so they had to kill it after a couple of iterations.

And by "nobody", you mean "actually a lot of people, just not as many as the bigger model". It's ok to have a model that meets a less common, but still extant, need in the market. If everyone followed Apple's logic on this, people with very small or very large bodies would have to go naked because companies would go "that size doesn't sell as much, we have to kill it" rather than (as actually happens) charging more per unit to make up for the overhead of lower volumes of sales.

The mini accounted for 3% of sales. Personally I’m a believer, and a buyer, but 3% isn’t a good number.

It's not ok if it uses resources that could be better spent elsewhere. At 3% share what do you expect them to do?