Probably because they could easily have given the same advice without needing to call people on hn that encourage and support open source software "low-class".

>Why the downvotes?

Probably for calling open source developers sad low-class beggars. Also probably for the presumption that OP should be trying to hustle an income from a fork of an open source project that no one would be willing to pay for anyway, because there's no market for 2d renderers. They're all already free.

It isn't only crass, it's stupid and crass.