I've made most of my money as a software developer. As an old business partner of mine used to say, that's a "butts in seats" business.
I needed something that was making money while I slept, so I started a print-on-demand Shopify site. I used my dev skills to build some tools to quickly populate my shop products plastered with phrases I had made up.
I wasn't able to figure out the marketing for that store, but then I realized that the tools that I built could be useful to other people. That's when SwAag was born.