The great profit margins tend to be in branding though, not OEM work. This is a huge hurdle Taiwan's industries in general have to overcome (HTC and Foxconn are Taiwanese), and probably part of the reason Foxconn bought Sharp.
Not that it cannot be done. Acer is a prime example of an OEM turning into a full blown brand name. HTC seems to be focusing on too many thing and for the last ten years have been feeling like they were missing something to match the line up of other phone manufacturers.