Because AMD is a company with a long history of making crappy processors, that only recently created a decent one, by lucky coincidence. Intel is exactly the opposite.

Even now Intel architecture is still superior in some areas, the biggest downside of it being the fact that they are stuck on the outdated 14nm++++ process.

Once the Intel's 7nm comes out there will be no reason to buy AMD, except for the price (I expect Intel's 7nm process to be roughly equivalent, or even superior to TSCM's 5nm)