Realistic WWI flight sims are a very niche market. In fact, they are a small niche market within the already small niche market of flight sims in general. Those "flying games" that are successful these days are mostly arcade style combat such as War Thunder.

OBD is still developing WOFF out of passion and they have more plans for the future but some additional $$$ never hurts. WOFF UE is already the most content rich WWI flight sim ever produced but there are many of us who would like to be certain that whatever other ideas, planes, features, content or improvements that OBD has in mind will be certain to make it to market. We might be a small player base but we are nearly as passionate about WOFF as the developers.