The second worst after shaytan is Fir'awn (Pharoah). He claims to be;
1. Rabbi al Naas:
Then (Pharoah) said - I am your Lord the most high. (Nazi'at 79:24)
2. Malik al Naas:
Don't I own the kingdom of Misr/Egypt? And these rivers flow beneath me? Do you not then see? [Zukhruf 43:51]
He is referring to himself as malik/king/owner.
3. Illaahi al Naas:
And Pharaoh said, ‘O [members of the] council, I do not know of any god for you other than me. So kindle for me, O Hāmān, [a fire] over the clay, and bake for me bricks [of clay], and make me a tower, a lofty palace, that I may take a look at the god of Moses, to observe him and inspect him; for truly I consider him to be a liar’, [al Qasas 28:38]
Pharoah declared himself to be Rabb (Master), Malik (King) and Illaah (god) And this is what Dajjal will claim to do too in gradual steps as his power grows.
That is what the waswasa/whisperings of shaytan can lead to a person too. Source
The biggest fault of shaytan is arrogance. And this is what he wants to instill within us through his waswasa. And this is how Pharoah was led astray by him. Today we are living in times where people claim to be their own Master, king, and their own god who makes the rules of haraam/halaal for them.
Have you seen he who has taken as his god his [own] desire, and Allah has sent him astray due to knowledge and has set a seal upon his hearing and his heart and put over his vision a veil? So who will guide him after Allah? Then will you not be reminded? [al Jathiyah 45:23]
We are living in a time where we are living in societies of people being mini Pharoahs. This ego problem is the root cause.
Shaytan recognizes that Allah is the Creator (he said to Allah as mentioned in the Qur'an; khalaqtanee min-naar - You created me from fire) - but he wants people to forget that Allah created them. A clear example of that is Pharoah.
Naas has several meanings, and one of its root words is Nasiyya- to be forgetful.
A power Allah has given shaytan is to make people forget. The biggest thing people forget is that Allah is watching them.
Satan has overcome them and made them forget the remembrance of Allah. Those are the party of Satan. Unquestionably, the party of Satan - they will be the losers. Mujadija 58:19]
We seek Allah's protection not to be forgetful, and to be of the rememberers of Allah's Reminder.
So when you recite the Qur'an, [first] seek refuge in Allah from Satan, the expelled [from His mercy]. [an-Nahl 16:98]
Because we might recite the Qur'an but we forget what we are reciting it for. In surah al Kahf, the servant of Prophet Moses/Musa left the fish (a meal) from where they had left on their journey.
One of the best ways to fight the shaytan's whisperings is to remember Allah. The more Allah is remembered, the less likely shaytan can have control. The only time he can go in your chest is if you are not remembering Allah.