Hypocrisy might be a bit of a strong word for this, but it's feels close to it yeah. At least, since money is involved.
Before sim racing, I've only knew modding as a "volontary free content" : I don't really remember of a single one that wasn't free, even the big boys. "Lost alpha", the complete (!!!) re-creation of the original game of Stalker (twice the lengh), was all free. Any full scale map of Morrowind, totally free. Everywhere I was going, for years and years, it was always the same song : "It's only fair because it's free". Because a mod is, by essence, not legal, so you're not hurting anyone if you don't get any money for it, right ?
And then I discovered modding in sim racing and oh my god you don't care at all for that motto here, do you. Patreon this, patreon that, paying for conversions, paying for a mod of a mod, etc... And the line between good and evil as a moral value and intellectual property become, well, shattered ? So... Is it hypocrisy ? I agree in a way. In another one, I'd say it's simply another culture, another point of view on content creation and video games in general. And greed. Lots of it.