The biggest reason why windows still has that grip vs linux is hardware based.

Try installing Ubuntu on a brand new laptop. Its just not something a non technical user can deal with. I am sure a good share of us here on HN has, at-least one relative who calls us because the "internet is broken" imagine them trying to deal with something like ubuntu on a brand new computer.

I like to think this is partially our fault as consumers, we need to actually do more to demand hardware vendors to support Linux. Especially laptop manufacturers.