Thiel speaks from the perspective of the monopolist, pithily condensed to 'competition is for losers'. Any product involves a set of trade-offs, and decisions. It is not a law of nature that the monopoly product makes trade-offs everyone, or even anyone, is happy with: people could identify ways the product could be improved. But under a monopoly they can't vote with their wallets. Consider Microsoft in the 80s and 90s. They were, realistically speaking, the only game in town. What efficiency did their monopoly help achieve, and why did it justify the stifling of choice? Maximizing efficiency is a more tenable argument when the product is undifferentiated, which is not the case in technology.