Streaming multiprocessors. That's the reason. Nvidia has an extremely complex SM architecture that CUDA is based off of and AMD/Apple focus on simpler ones because they thought it was more power efficient (oops, it's less power efficient: https://browser.geekbench.com/opencl-benchmarks)
This is such a surface-level factor in the discussion that I don't even know why you'd be offering your advice on Nvidia if you can't tell why people own their hardware in the first place. We've been having this GPGPU discussion for like 12 years at this point... people insisting on their opinions without understanding what Nvidia does is how we got in this mess in the first place.
You're talking about a market where the ASP for AMD is like 450 bucks and NV has 10x the market share at a 50-60% higher ASP. Then you look at Intel Arc, which has an ASP somewhere in the 200 bucks range. I don't think these market shares are primarily dictated by economics and the commodified properties of GPUs (compute power etc.), but rather different things, like software.
In any case, AMD is clearly focusing on data center applications and is starting to enjoy some inroads there.
AMD cutting prices won't affect the biggest thing: CUDA is the software basis of machine learning, and creates an effective hardware manufacturer monopoly. You have to buy Nvidia, to get a good CUDA experience.
Nvidia has 9x(!) the discrete GPU marketshare as AMD. Nine times! AMD cutting prices would help them increase that.