That's some kind of logical fallacy... sort of like saying... "if you think that aircraft carrier is overpriced, you should build one and sell it yourself."
One can determine objectively whether something is overpriced based on comparisons with competing products.
If an aircraft carrier is overpriced then there is a market for cheaper ones and you can make a bundle by putting your money where your mouth is (assuming you are right, of course).
If making aircraft carriers is not your thing then you shouldn't be telling other people how much to charge for theirs.
The only reason multiple competing products would come in to existence is because of people going the first route.
One can determine objectively whether something is overpriced based on comparisons with competing products.