But when such projects take on tens/hundreds of millions of funding, it is inevitable that the technology becomes secondary to paying back the investors 10x, no matter what. Ironically most of that kind of funding seems to go towards sales and marketing rather than R&D. Usually core committers are only a minority of employees in such companies and things get worse when that no longer includes the C-level executives.
This creates a lot of friction when inevitably somebody else undercuts such projects in terms of quality, features or price. This is inevitable because all software eventually becomes a commodity. Your fancy pants DB clustering solution might be shit hot this year but you can bet there will be half a dozen projects imitating what you did within years.
This is basically what is happened to mongodb. It's all about diversifying, "adding value", proprietary extensions, etc. for their paying customers instead of doing what they were good at for all their users. And courtesy of the license, copyright transfers and outside contributions dry up and it's all on the company to do everything in house. Great, as long there's money but when that dries up it creates problems. Meanwhile projects like postgresql and others provide more or less drop in replacements, because they can and because there are users and developers in having that. Apparently they are still doing fine in terms of share price. Best of luck to them but I probably won't be using it.
Most healthy OSS projects out there have licenses that are well understood from a legal point of view and battle-tested in years/decades of use. Some have quirks that need working around (e.g. the classpath exception for GPL v2), others are fine as is (e.g. Apache 2.0). They also have a plurality of copyright holders spread over many companies that makes re-licensing impractical. Most such projects have a core of developers that are typically employed by a big company taking an interest in the project. Having key people in key projects is of strategic importance to them and ensures their interests are taken care off.
The whole point of OSS is commoditization and pooling resources between otherwise less likely to collaborate companies and individuals to get things done better than each of them would be likely to achieve by themselves. That's why most operating systems these days are largely made up of open source software, much of which has had multiple generations of developers working on it. Most of the build tooling around that, same thing. Apple, MS, Google, they all ship mixes of proprietary code and OSS code. Quite a lot of this stuff can be traced back to the early days of unix. Almost every big fortune 500 software company out there pays people to contribute to and represent them in OSS projects that are vital to their business. Even the less popular ones like Oracle actually contribute a lot. That's not charity; it's key to their success.
MS just retired two generations of their in house browser in favor of an open source project primarily backed with Google and with significant portions of Apple contributions from back in the Webkit days. If you'd have to choose two competitors for MS, those would probably be at the top of your list. Why did they do this? Browsers are a commodity and they were negatively differentiating with their in house efforts (as demonstrated by world + dog installing something else). They tried to fix it (Edge) and it didn't work out. All of the surviving browsers are now built around open source projects. I think Edge is probably going down as the last non OSS browser to be widely used.
I use open source components, libraries, and tools for almost everything I do. I love Github. I share code there myself. Most of the stuff I depend on has neither VCs nor much corporate funding behind it and its fine. Some of it does have VC funding and its also fine. My life would be hell if I had to reinvent all those wheels.
I agree funding OSS development is key but I don't agree that that needs to primarily come from companies that own the software and sell licenses+support. That's not how most OSS software I use works; it instead thrives on companies using and paying for people to contribute. Nginx is one of many software packages that I use. I don't think I'll ever pay for licensing or support; because frankly they are relatively unimportant to me. As for the dozens of npm dependencies and their hundreds of transitive dependencies, nope. Not a cent. I would probably consider SAAS solutions when it makes sense; as I have done with e.g. Mariadb and Elasticsearch. But mostly OSS works because it is free as in speech and beer.
In the case of nginx, there are dozens of OSS web servers out there. It's just one of many moving parts I need to worry about. I'll pick whatever is cheap and convenient.