I think Metcalfe's Law [0] for networked services is a bigger driver for winner-take-all, than needing deep pockets to compete in a mature product category. For consumer products, a small number of large players can own entire market segments between them, but still compete with one another, as we see in other capital-intensive industries like cars or smartphones. (And it's fair to see that as its own problem; but it generally devolves to the question "if markets are universally the most efficient form of exchange, why are firms a thing?" [1].)
Not necessarily, especially in areas like sound where it is essentially ‘solved’
Why should humanity put so many resources towards improvements that no mere mortal can notice? It’s probably better to put the talent on other problems...
[0] https://en.wikipedia.org/wiki/Metcalfe%27s_law
[1] https://en.wikipedia.org/wiki/Theory_of_the_firm