I think it is fairly simple why : they all have ‘stars’, the levels. Humans are born with no level at all, they are zeros. In a world where your importance is determinate by your stars, not having any makes you equal or lower than a kuriboh (ouch). Or at least is my assumption. 

So what if one of the reasons why Judai became evil was so he could prove to these monsters that while he may be a human he’s still important and powerful and he wanted to use his power to get rid of that hierarchy bullshit and make others revere him because of his power and not because of his race?

Yes and no

A recurring theme in GX was all this hierarchy bullshit. They spent half of season 1 establishing Judai as the underdog wonder janitor, having people dismissing him as some inferior being the entire time due to his status as an Osiris, as if the only way to prove his worth would be raising from a Osiris to Ra and then to Obelisk. Judai himself had rejected his promotion, as he probably dislike this idea of having his worth proven by something as stupid as the color of his uniform - to him all duelists are worth, no matter if they are good or bad at dueling, as long they enjoy themselves and truly like their decks.

Season 2 was basically all about being part of an exclusive, pure-breed elite too. An exclusive club where only the ones who were invited, the chosen ones, could enter. 

In season 3, he was already a hero and this ‘chaste’ system didn’t mattered anymore. And yet it saw it happening once again, and it was even worse than what he had lived himself so far. The system is unjust, broken and needed to be brought down. Besides, Birdman begged him with his dying breath to bring this system down. That certainly caused a big impression on him. Specially after the duels against Satou and Cobra.

I don’t think he wasn’t trying to show the monsters as a whole his worth as a human, but to everything that the hierarchy is wrong everywhere - monsters and humans alike.

idk if I expressed myself correctly, through XD

No, I understand it. And you’re absolutely right. So he’s not just proving it to the monsters but to everyone no matter who they are and his message was “This hierarchy nonsense must end now.”? To Judai you should succeed if you are worthy because of your own power and not the circumstances of your birth.

This is exactly the message he wants to hammer into their heads by having Neos punch the hell out of Bronn until the dude become a puddle on the ground (if they could bleed)

I hope Neos can turn this psycho into a stained glass window.