I ran a private server years ago. Two things people in this thread are getting wrong:

The engineering is way harder than anyone gives credit for. You're reverse engineering a server protocol from the client binary, writing your own spell systems (thousands of spells, each with edge cases), pathing, instancing, combat mechanics. Then scaling it for a few thousand concurrent players on hardware you're paying for out of pocket. Turtle WoW went further and built new raids, zones, races on top of all that. That's not modding, that's game development without any of the tools the original team had.

The "they made millions" framing is always misleading. You start as a hobby, players show up, hosting costs get real, you take donations to keep it running, and at some point your paypal has six figures running through it over a few years. None of that is profit, it's servers and bandwidth and people helping keep the thing alive. But in the lawsuit it gets presented as revenue from a commercial enterprise.

Blizzard is right to protect their IP. But calling this a simple piracy operation misses what actually happened.