Not really a programmer but was in a similar stream. I trade stocks/options now.

I worked really well with excel sheets (macros) and was able to calculate an edge from watching data which was available to me. Maybe your work has a problem you can solve and it would work for other companies.

I had to get the same data at that time, now it's easily accessible, and enough capital to implement the strategy full time.

I had to learn to program a different language which created the active income stream.

Ask yourself what do you like doing? Then work on it in your spare time. What's fun for you? For me, I wanted to make money without working hard. I also love money.