Thanks for you comments.
GSX originally came out in 2012, and we don't consider it "finished" yet.
Those smart users that supported us since then, have been upgraded for free through FSX: Steam, P3D 1.0, 2.0, 3.0, 4.0 and 5.0, sometimes with massive improvements that costed us months of work (like PBR support or 64 bit support) that everybody else would asked money for, justifying "it's a new sim, you must pay again", yet they all got it for free so, I'd say during those 10 years, those that bought it when it came out, got quite a bit of value from their investment.