Looks like you have not been paying attention. AMD have said time and time again that they are targeting the mainstream and performance segments first. Translation - $300 and down, where >80% of the market lies (in units). Their goal is to regain market share they lost last generation due to the 20nm debacle. So they will ship the mainstream chips first, with high-end later. Nvidia is going the opposite route releasing their high-end first, mainstream later. The end result is Nvidia is unchallenged in the high-end space, while AMD will be unchallenged in the mid-range space.
Don't worry, AMD haven't given up on high-end, there's Vega coming for that. Similarly, Nvidia haven't given up on the <$300 market, they have GP106 and GP107 coming (and possibly a further cut down GP104).