Where I used to work my colleagues used commercially available game engines to build simulations for training purposes. Many of these were for military customers although some were civil (e.g. a safety trainer for coal mining). I therefore became interested in game development in general and played around with Unity for a while at home. From work, I'd gained an appreciation of the many different skills involved in game dev. In parallel I'd been using Poser and Daz Studio for 3D scene construction, with Octane for photorealistic rendering. I'm also a hobbyist photographer, and enjoy playing with light.
I eventually realised that I most enjoyed photorealistic rendering and that the asset marketplaces were often swimming in shovelware - so there was no real money in asset creation. Not that I was looking for serious revenue, but I had wondered if I could make enough money to pay for assets and licenses. I'd produced some promotional renders for asset creators and eventually came to the attention of someone who produces tutorials. So I decided to combine my 3D lighting knowledge with general photographic experience. I've now produced tutorials (sold on the Daz 3D marketplace) focussing on lighting 3D scenes using Daz Studio (and historically Octane). One of these has earned me enough money that I actually think I need to declare it on my tax returns!
[Edit] I sometimes use Blender to create simple 3D assets although I've never really gone up the learning curve. The 3D tools in Photoshop although simplistic are also sometimes okay for my purposes - e.g. if I want some 3D text in a scene. I keep meaning to have a look at Unreal and its rendering capability, but never quite get round to it.