Of course it is! If you gain market share you are likely to hold on to it. You can then start ramping up prices to get your profits. Think of market share as a long term investment, once you get people to invest in your technology they are likely to upgrade with your hardware. Here's an example: If someone decides to buy Zen because it offers similar performance to Intel for a better price then they're going to buy an AMD compatible motherboard. When the time comes to upgrade their cpu that person is more likely to buy another AMD cpu even if it's a bit more expensive than the last generation because they already own an AMD motherboard and have invested in that ecosystem and a lot of the time feel emotionally attached to "their brand". This makes market share a very important objective. Just look at how it's helped Nvidia, AMD has had a better price to performance ratio than Nvidia for 3 generations now yet Nvidia still dominates. Why? The long lasting effects of market share.
Your argument makes no sense? If you price the product higher, sure, you'll make more profit per sale, but your sales will be low and you'll lose market share. If you price a product lower you'll make less profit per sale, but your overall sales will be high and you'll gain market share. The profit side of the equation will work out about the same, however by using a low price strategy AMD can gain back market share over Intel which is critical at this point and you couldn't do with a high pricing strategy.