AFAIK, Mike Schuffham (www.scuffhamamps.com) earns a living developing and selling S-Gear. It might be a semi-retirement or lifestyle type living - not sure - but he's been doing it over a decade now. He doesn't charge as much as he could and gives away free updates for far too long. Despite being a (mostly at least) solo effort, its widely regarded as being a top-tier amp sim. I personally think it sounds better than both Helix and Bias, which are both heavily bank-rolled outfits.

It doesn't have their breadth, but the tones it does have are nearly as good as it gets without serious air movement.