The Cathedral and the Bazaar meets The Tragedy of the Commons.
Let's say there's two competing options in some market. One option is fully commercialized, the other option holds to open-source ideals (whatever those are).
The commercial option attracts investors, because investors like money. The money attracts engineers, because at some point "hacker" came to mean "comfortable lifestyle in a high COL area". The commercial option gets all the resources, it gets a marketing team, and it captures 75% of the market because most people will happily pay a few dollars for something they don't have to understand.
The open source option attracts a few enthusiasts (maybe; or, often, just one), who labor at it in whatever spare time they can scrape together. Because it's free, other commercial entities use and rely on the open source thing, as long it continues to be maintained in something that, if you squint, resembles slave labor. The open source option is always a bit harder to use, with fewer features, but it appeals to the 25% of the market that cares about things like privacy or ownership or self-determination.
So, one conclusion is "people want Cathedrals", but another conclusion could be that all of our society's incentives are aligned towards Cathedrals.
It would be insane, after all, to not pursue wealth just because of some personal ideals.
This is pretty much a more eloquent version of what I was about to write. It's dangerous to take a completely results oriented view of a situation where the commercial incentives are so absurdly lopsided. The cathedral owners spend more than the GDP of most countries every year on various carrots and sticks to maintain something like the current ecosystem. I think the current world is far from ideal for most people, but it's hard to compete against the coordinated efforts of the richest and most powerful entities in the world.
The answer is quite simply that where complexity exceeds the regular person's interest, there will be a cathedral.
It's not about capitalism or incentives. Humans have cognitive limits and technology is very low on the list for most. They want someone else to handle complexity so they can focus on their lives. Medieval guilds, religious hierarchies, tribal councils, your distribution's package repository, it's all cathedrals. Humans have always delegated complexity to trusted authorities.
The 25% who 'care about privacy or ownership' mostly just say they care. When actually faced with configuring their own email server or compiling their own kernel, 24% of that 25% immediately choose the cathedral. You know the type, the people who attend FOSDEM carrying MacBooks. The incentives don't create the demand for cathedrals, but respond to it. Even in a post-scarcity commune, someone would emerge to handle the complex stuff while everyone else gratefully lets them.
The bazaar doesn't lose because of capitalism. It loses because most humans, given the choice between understanding something complex or trusting someone else to handle it, will choose trust every time. Not just trust, but CYA (I'm not responsible for something I don't fully understand) every time. Why do you think AI is successful? I'd rather even trust a blathering robot than myself. It turns out, people like being told what to do on things they don't care about.