> Society benefits when the mercenary and competitive urges of high achievers are channeled rather than opposed. That's the secret behind the success of modern market economies...
Big statement, unsubstantiated.
> the alternatives are clearly worse for everyone in a society, including the poor.
Big statement, unsubstantiated.
> they channel the results of capitalism rather than opposing it
This perspective is conspicuously self-serving, but it doesn't seem to be a very clear or elucidating one. What parts of capitalism are being "channeled"? What outcomes are you referring to?
Certainly the poor don't see benefits except where the rich are forced to pay back into public funds for redistribution. It seems to me that the results of capitalism are tempered by more regulated economies, considering the natural end state of capitalist pursuit is feudalism if left unchecked. The profit motive guarantees this.
> that's the only approach that really brings prosperity to a society
This was the popular narrative for describing the failings of Soviet-style communism re: economy. But it stinks of essentialism. Actually, your whole argument does. The reason the CCCP crashed has been studied in more detail now that we have the benefit of hindsight. The rest of the global economy was capitalist, and furthermore, was shaped and organized by a select few power players to engineer the demise of CCCP by creating conditions of brittleness, so that relatively small disruptions (eg localized famines) would cause knock-on effects. There is a direct throughline to today: see all the talk of sanctions vs "the West's" enemies, which amounts to nothing more than exactly what is described above.
> One person's success does not prevent another person's success.
An unqualified notion of "success" seems to be used here. It is not clear even what you think is "success". Seems to be some abstract Enlightenment-style ideal that has a murky-at-best connection to material reality.
One person's consumption prevents another person's consumption because we are limited by the law of conservation of mass-energy. One must consume to innovate. Hoarding and asymmetric investment limit the distribution of these resources to those who may be able to utilize them more effectively, because they can contribute their own IP. This, in the language of basic economics, is called an opportunity cost, and the point of economies (insofar as there is a point) is to minimize that cost. Seems pretty obvious to me, interacting with people from varying levels of class and societal rank, that this cost is harming our progress.
To think we have reached any kind of pinnacle of societal organization demonstrates a depressing lack of imagination. Conservative philosophy has a long way to go to properly argue its side -- and unfortunately for conservatives the work done to advance systems science over the last couple decades has done a lot to tear down the fundamental tenets thereof.