I think the popularity of the Keurig's(and clones) have a lot to do with the legends about how difficult pour over coffee is along with the fact that American's don't really have electric kettle's nor coffee grinders.

So for the cost of one overpriced toy the Keurigs lets you play at being an coffee snob without really having to learn anything about coffee or how to use an grinder or buy an electric kettle and that speaks to a lot of people.

And we should not forget that if your only experience with manual coffee makers and grinders is watching some internet coffee snob use massively overprized equipment and obsess over every little detail the process of making coffee the old fashined way might seem overwhelming.