Game engines are different. It's a tiny market relative to web, and really the only people in the market for an engine other than Unity or Unreal are indies, who have near zero revenue and even less willingness to spend it. Those two are so far ahead in terms of features, support, and battle-hardening that you'd pretty much have to be insane to pick anything else if you had paying users.
Always be wary of any market where someone's willingness to try your product is in itself a negative indicator of ability to pay. Hit-driven markets that attract large numbers of non-serious dabblers are extremely difficult to sell tools profitably to, but it's easy enough to get minor attention that makes you think you might have something worthwhile (music production is another one that scatters corpses all over the place despite seeming large at first glance).