I don't know about "very expensive" unless you're in the market for a bargain bin computer. A Mac Mini costs $599, an feature equivalent Dell is maybe $399 to $499, so there is a price premium but it's not outrageous. Plus, you do get significantly better support from the retailer, cheaper upgrade options on the operating system, and a lot of bundled apps that, for some people, are more than worth the extra dollars.

It's not that people are not afraid to learn new things, they just have priorities, and often "learn a new OS" is not on their list.

Remember, Linux has succeeded on Android, so don't think it's impossible for people to use it.