I think he set himself as a badguy that only Paradis could take down so that the world would be less likely to just eradicate Paradis out of fear of their power like they were already angling towards wanting to do. I ALSO think part of the point was that this was a stupid angle to take, and it happened because those who end up in power during war arent always those who are great to have in power during peace times. I think Eren admitting that it ended up this way because he’s an idiot who couldnt come up with a different way hints towards this message