That's simply not the case. Talk to most people and they'd prefer that their entire digital lives weren't dominated by a few megacorps with access to all your private data. It's true that a lot of people have no idea how to begin achieving that, but that's not the same as not caring.
The problem is that when you develop a new system, privacy and decentralization generally aren't things that can be easily added in as later optimizations. If you care about those things then you need to build them into the design from day one, and they are hard problems to solve. Something as simply as resetting a forgotten password can turn into quite the challenge when there is no centralized authority. Getting to the point where your basic decentralized and secure platform works well enough that you can build stable, user friendly apps with all the expected niceties takes a lot of time and thinking by highly skilled developers and many projects never fully get there. This doesn't mean that it isn't worthwhile to attempt to develop such technologies.
There is also a weird fallacy going on here around building stuff based on a shallow perception of what consumers* supposedly care about. Looking at the current social media landscape and thinking "this exists because it's what people really want" betrays a particularly narrow way of thinking about the economics and power dynamics of the modern internet. This type of willfully naive thought process would have us optimize toward a highly profitable software skinnner box. The wetware equivalent would be to suggest that we design the most profitable and addictive drugs. After all, consumers are consuming them so that must be what they want, right? Why are you building something that isn't optimizing for maximum consumption? You must be blinded by your own weird ideology or blinded by interesting but irrelevant technical challenges.
Then there's the weird comment about exciting technical challenges not necessarily all being businesses. The author seems to have an underlying assumption that if it's not a viable business then it shouldn't be worked on.
*Thinking about participants in a two-way global communication system as simply "consumers" seems in-line with the rest of the author's thought processes