Open core is at least something (and I'm forced to agree with you, IntelliJ mostly kills everything, I capitulated and ended up adopting the community version recently against other IDEs, initially for its Java debugger) but you can pay devs full time with completely open source stuff.
Companies are more than willing to pay for support, consulting or even paid pre-built binaries that come with a bit of support, when it's more convenient.
Again, not saying it's easy, and each project is different, but that's something possible.
Most successful open source companies I can think of are server-side applications or Linux distros, where the company sells support or hosting. I'm not sure how that would work for a desktop app.
Yep, you got this. We also sell open source extensions (yep, you could build and download the code, and strip the license handling, but somehow companies will pay for the convenience of having the install and upgrade done automatically - they also know that they support the company behind the thing they use, in a way that can be easily justified to their accounting department, with an invoice, and get some support hours included, which they like. Paying for something that is paid is easier than donating!). And we also do (a lot of) consulting.
For desktop applications, it might be harder indeed. Though JetBrains does have an extension store and could do the same, and also sell support.
Not sure about the consulting, but why not? Maybe they could sell some of the expertise they have on actually a big number of topics. I'm sure companies would be eager to pay them to implement feature in their IDEs they need, or to build components specific to their setup / projects. I'm discovering that companies will spend money on all sorts of things, I'm actually somewhat surprised by this.
Igalia [3], for instance, does this with browsers. They sell consulting around browsers and also get paid to contribute features in the big engines.
I mentioned curl earlier, Daniel gets paid for doing commercial support on curl [1]:
> I work for wolfSSL from home doing commercial curl support. If you need help to fix curl problems, fix your app's use of libcurl, add features to curl, fix curl bugs, optimize your curl use or libcurl education for your developers... Then I'm your man. Contact us!
There's also MediaInfo [2], an open source tool to get all sorts of information on videos. They get paid to implement features and to do consulting.
I'm sure you can sell support / consulting for all sorts of things.
> What company are you working for?
XWiki.
I love open source, but OP isn't wrong to decide to prioritize building a sustainable business over releasing their code.
Whether you personally prefer the guarantees that FOSS provides or the benefits that having salaried employees working on the project full time provides is a personal decision.