This is what I want to do. By far my favorite roles in my career have been when I get to work with deep domain experts in some research-oriented niche. I'm in one of these right now (in the clean energy space) and it's awesome. It's very motivating for me to collaborate with them and build tooling to accelerate their work.
But it also makes me feel that, even though I'm in my late 30s, when I grow up, those people I love working with are who I want to be.
It may or may not prove to be unrealistic, but my plan is, after my kids are a bit older and we have saved a bit more liquid assets and have refinanced to a lower mortgage payment, to enter a graduate program for something interesting, and maybe keep working on software part time while I do that.
I'm old and more likely to retire than start anew, but that's something that still calls to me. Got a doctorate in anthropology but wasn't entranced by academia. But science itself is interesting. In retrospect, I think I should have gone with physics, but... my dad did that, and it's a tough gig in many respects. (Governmental research funding is very inconsistent.)
When you're retired, and don't need the funding, there are plenty of under- or un-funded research projects that can be done. The right professor would likely be open to collaboration/guiding work like this, particularly if your PhD augments the skill set of their group/lab. You don't need them necessarily, but it might help to bring you up to speed with publishing (assuming that's your goal - and if you're doing research, I think it should be. You want the work to persist after you if possible). Proposer and funders are pretty good at figuring out good use of limited resources, but they just can't fund everything and there are many un-turned stones.
But it also makes me feel that, even though I'm in my late 30s, when I grow up, those people I love working with are who I want to be.
It may or may not prove to be unrealistic, but my plan is, after my kids are a bit older and we have saved a bit more liquid assets and have refinanced to a lower mortgage payment, to enter a graduate program for something interesting, and maybe keep working on software part time while I do that.