Don't underestimate the huge economies of scale that the Chinese companies are operating with. And not just on parts - on labour too.

When you buy Jolla, you're not just buying the hardware, you're also subsidising Sailfish OS development costs, salaries for staff (which in Finland are higher to begin with), rent for the HQ and everything in between. When more devices are sold, this part (as a share of the cost price) can be significantly lowered.