Marketshare is one metric that only has value in a particular context. It says something about population, but not who that population is, whether it's growing, their influence, and so on.
Consider a different proposition: India is the most dominant nation. After all, they have the most people, end of story, right? No, of course not. India might agree with that but few others will. The US has been the dominant global nation since WWII (for good or ill) despite only having 4% of the worlds population, compared to India's 16%. Is the US dominant in every regard? Hardly. Military, yes. International influence, yes. Economic, yes. Influence in technology, yes. But it also leads in incarceration, gun violence, CO2 emissions per capita, and a a bunch of other, not positive things.
So consider military. The US is militarily dominant because that is measured against other nations. Sure, there's a pure 'money spent on the defense spending' aspect of it, but there's also more direct measures - size or power of military, general handicapping of head-to-head conflicts, etc. But does the US dominate on civilian guns? No. Because that's not a contest. France isn't trying to win that one, and consider the US being a leader there as a kind of failing.
So how do we normally consider dominance? By how one party force actions on the part of other parties. The US forces other nations to respond to it militarily. China is shaping their military directly around the US because that's the conflict that they need to be prepared for - both strategically and tactically. That's generally how we consider dominance - who is acting and who is reacting. Finding metrics for that is hard.
In tech, marketshare is certainly a component of it, but generally that's used as an easy rather than good measure. It's easy to count noses. And in a lot of cases, that's good enough. But not always. Counting Indian noses vs American noses clearly isn't adequate. It's not that Apple doesn't care about marketshare, but it's not what they care about most. Nor is it what Android cares about most. Google cares most about the aggregate revenue and profit off of Android. That's Pixel plus Play Store, plus not having to pay for customer acquisition on that share of the market (Google pays Apple about $15B/yr for search priority on iOS - that's a check they don't need to cut to Samsung, paying their engineers instead). Well, Google earned $280B, and Apple earned $205B just off of iPhone hardware sales - not including AppleCare, App Store, accessories, other service revenue, and so on. There is no question that iPhone is more valuable to Apple than Android is to Google in total aggregate - all secondary and tertiary benefits included.
How else can we determine dominance? Who is acting and who is reacting? Headlines on iPhone killer were dominant for a while, was there ever headlines of 'Moto 360 killer'? 'Samsung Galaxy killer'? No, everyone was reacting to Apple. Android is still primarily reactive to iPhone. Not always. I'm reminded of those Android phones sold in parts of Africa that have a built-in flashlight - like, full on flashlight - not the camera flash turned on. That's very clearly a narrow market innovation that was in no way a response to Apple, but by and large, Android primarily reacts to iPhone. Sometimes iPhone reacts to Android, but usually in minor way 'Apple copied the notification style!'. Yeah, okay, sure. But Android copied the entire form factor. Android is somewhat infatuated with folding phones right now. Apple doesn't have one. And Apple hasn't rushed to match that. Apple doesn't NEED to react to the folding phone trend. In fact what Apple tends to do is to look for a better implementation at solving the problem people buy folding phones to do, and make that the desired solution and force Android OEMs to respond to that. That's basically what Vision Pro is - deconstructing what people like and dislike about AR/VR headsets, fixing the flaws, adding the missing bits, and putting that product out there. They aren't even attempting to compete with PSVR or Quest. Anyone want to bet that Meta feels compelled to respond, though?
Consider this. iPhone launched in 2007. We know the famous response by RIMs executives to the iPhone. But Blackberry not only grew unit sales, revenue, and subscribers through mid-2011, they usually accelerated though that time. iPhone didn't overtake Blackberry market share until mid 2011. But Blackberry started seeking someone to buy the company 2 years later. If marketshare was a useful metric, it should have informed us that Blackberry was dominant from 2007 through 2011. Does anyone agree with that? Was it dominant? Did the company fail just 2 years after dominance? No, even though iPhone had effectively zero marketshare in 2007, it was dominant. A lot of people disagreed that iPhone was dominant - not just RIM executives, and Ballmer, but also folks in the battlefront and a LOT of Blackberry owners. But I think we can now agree that iPhone was dominant. RIM had to pivot to Blackberry 10 in order to compete with Apple. Apple never responded to Blackberry. They never added a physical keyboard, or any of the services that RIM proclaimed that customers couldn't live without. Observers could look at all kinds of metrics on iPhone vs Blackberry and see lines going up, marketshare ranking, etc. And if you invested based on that, you got fucking wrecked. If you made a strategic investment in the platform for your company, you looked like an idiot. Those were the easy metrics, not the useful ones. I have experience in data science. Most metrics are easy, virtually none are useful in isolation.
I've been an Apple investor for 25 years - since before Jobs became CEO. Retired early thanks to it. Marketshare factors in a little bit, but not much. If I had chased it as a metric, I would have invested in a LOT of failed companies and never Apple.