My first 'real' project was a mobile game I did. I created all the assets and coded the entire thing with a framework I made (wrapped around the Android SDK). I honestly had no idea that modern games (and software in general) are pretty much all made using existing engines and frameworks. It was pretty eye opening when I'd be browsing game development forums and see people posting games like, "I made this in like a week", and it'd be a decently polished game. Meanwhile, my point and click game took almost a year.

So that was the most important lesson; open source and free libraries are plentiful, time is valuable, and don't reinvent the wheel (unless you have to).

The good news is I wouldn't need a whole lot of sales to equal what I make right now. I live within my means and live frugally, I'd just love to have more time to focus on doing projects I enjoy and upgrading my skills.

I've always had a very dystopian view of working at any tech related company, and SJWs have started to give that view some merit, I think.

But, this might make the most sense for the time being. I just never wanted a corporate job to kill my passion for exploring tech.

That's what I want to be doing, but unfortunately splitting my time between doing my own projects and menial labor full time is starting to get me.

WP themes was where I was leaning, but like my gaming example I imagined the market would be thoroughly saturated.

Yeah, that's always been my problem. My curiosity tends to take me all over the place.

I'm curious, though, as to what you consider a good foundation?

I would start learning an API. Maybe Google around for 'Java GUI APIs' and make a small application that you'll use for something.

Since you're using Java the Android Development Kit might be worth looking into as well