Infrastructure software pays exceptionally well and companies will pay impressively large amounts of money for it. You just can’t deliver a commodity product that has a vague equivalent in open source. I always recommend using open source first, if it will work, and I literally sell closed source database technology. Open source doesn’t come close to competing with anything I do, so it isn’t a threat, and the market for what open source can’t do is astronomical.
There is a booming market for state-of-the-art infrastructure software but that market is no longer retail and it doesn’t publish much, because that business model no longer makes sense. An uncomfortable fact, but one that many enterprise customers acknowledge, is that open source database technology (the part of the business I know) is quite poor. If you want to get paid in databases, produce software that offers an order of magnitude or two higher efficiency, scalability, throughput, etc on the same hardware than anything in open source. Companies will happily pay for that because it saves them millions of dollars a year in OpEx alone.
The economics works just fine, better than fine actually. You just need to deliver a product that materially outperforms the not-that-high bar of open source. This market is huge, it just isn’t as visible anymore because they don’t do marketing on billboards in Silicon Valley.
The real issue is that there aren’t enough people that can design infrastructure software that is materially better than open source. There is a large skill gap.