How do you develop a clear vision?

I hope you didn't write this whilst actively trying to start a family. Some advise you need to fall in love with the problem not the solution. That kind of advice doesn't usually hit home unless you have an epiphany moment. But you are definitely sitting in the "wouldnt it be cool if" room. You can argue you have a vision, but you don't have a problem. What do people in your current industry struggle with? What do people in an industry you want to work in (music maybe) struggle with? If you can find pain then there's an opportunity. Otherwise you can look at what sells in that industry and find something you think you could do better or compete with. Your bad-mouth app is one of those things that could go viral and make money but is more likely to flop and the chance of being successful is just a lottery. Best of luck!

Join a startup! Joining a new and small team forces you into a mindset of action and experimentation without having to use your own savings to fund the project. You'll learn a lot about user centric ideation and staying lean (if you havent read the Lean Startup, I'd recommend).

With your own projects, as other comments have said, focus on people first. Talk about your ideas and work on the ones that people seem interested in. Then iterate. It's that feedback loop that often propels projects forward.

Just keep making. At the end of the day it's all about enjoying what you do and there is nothing wrong with holding a 9-5 job whilst creating some fun half-finished things on the side. Startups actually take more of your time and energy than most jobs, and there's MUCH more to life than work. Maybe start a portfolio or a blog and publish a few of your works. I bet with a little effort you could scrub up a few of your old projects and host them.

...and it's absolutely 100% evident that the vision comes before the tech development or financial incentive.

Now, before the vision comes, there's something else that you're missing. It's the experimentation/discovery phase, where the seeds of a vision will start to evolve. For people like us (I'm the same, but with more than 100 projects started than dropped in the course of sth like 7-8 years), it's very important to do something, anything. To get the ball rolling.

The thing is that the vision will come when you are half way on your journey.

And this is where I would disagree with you:

Something I agree with - yet can't find.

It's exactly the opposite. You can find your vision. It's a proactive process. You have to sit, think, do, experiment and reflect on the results. There's no shortcut. No vision comes from the clouds as a gift. You have to earn it. It's work, man! As I said, before the vision there's work, experimentation, discovery! Make sure to think about this before you form a strong opinion, it's important. I see that you already did form it, and that's where your problem is, from my perspective ;)

I would suggest you two mental experiments.

• Stop taking in inputs. Like videos, podcasts, reading startup articles, books etc. Instead, start producing output. The problem with the input is that even though it might be valuable, it biases our perceptions. You have your truths. You have your world around you. You have your ideas. Stop over-biasing yourself for at least a week (a month is what I would suggest) with other inputs. Reflect a bit on you and produce some output. Do something simple and see how the outer system (users/communities/etc) reacts to it. Learn by doing. And don't even bother for the vision. It's too, too early!
• Reflection. Here's how it goes. I must warn you, it's not as sexy as it sounds. Take a notebook (not digital, physical!) and a pen/pencil, sit down and start drawing/writing. Put all of your thoughts on the paper. Even groceries, birthdays, what your wife said that frustrated you, a thing you've read somewhere that's stuck in your head, draw your cat, whatever... Put down everything that's in there. Then, start drawing some arrows. Start connecting thoughts. See patterns. See what bothers you. See what excites you. See the crap that came out and see if you can use it to make something out of it. :) Do this for at least one hour. At least. When I do this exercise, I always think I'm done after 10 mins. I feel empty after that. But when I push myself a little bit more - I get a lot of hidden thoughts, ideas etc. on the paper and usually the things that I manage to get out of my head in the second half an hour are where the magic is. Now, this is your mental clutter. It might have some gems in it, it might not. You might have to do it several days in a row to start seeing something. But get that out, I would suggest. See it. Seeing things is powerful. Holding things in our heads doesn't work, it just weighs.

Try my two exercises for a while. They are quite simple, but very, very powerful. Focus on 1) no input and 2) seeing your thoughts on the paper. I do exactly those two things and the results are fascinating. I'm not guaranteeing that it's going to work 100% for you. But give it a try and come back to me to share if it made some difference. :)