I read your comment and then went to lunch where I did a lot of pondering. Perhaps the code determines if you're "winning" based on the circular progress icons on the left side of the Victory Screen. Maybe the closer it is to being full the more hate will be generated by the AIs?
If that's the case, then my particular problem with extreme modifiers might be due to using the
Reformation Victories mod by
@greyTiger . That mod tends to show me as being closer to victory than I really am. For example, the Territorial Victory requires your empire to have the most land (minimum 35%) and you have to research Telecommunications. If I expand quickly, I can reach that 35% early in the game and the progress circle on the Victory Screen will be almost full despite me not being remotely close to researching Telecommunications.
I'll have to try a game without that mod enabled to see if the modifiers are more reasonable.