Arrogance is simply glorifying one's self while looking down on others. This could be as a result of one feeling superior to others based on wealth, knowledge, faith or background. Arrogance leads to the need to be praised by others. He who is arrogant is simply following the steps of shaytan. Arrogance was what led to the downfall of shaytan as he felt he was better than Adam and hence didn't prostate when he was commanded to.

"Allah said: "What prevented you (O Iblis) that you did not prostrate, when I commanded you''? Iblis said: 'I am better than him (Adam), You created me from fire, and him You created from clay.'' - Q7:12

The Prophet (SAW) said:

"Whoever has an atom weight of arrogance in his heart will not enter paradise." - Muslim

"A man shall glorify himself until he is written among the tyrants, so that he suffers from what befell them." - Tirmidhi

"Whoever has an atom weight of arrogance in his heart, Allah will throw him in the hellfire on his face." - Muslim and Bukhari

The arrogant person fails to realize that if he proud of his amassed wealth, it could be taken away from him. If he is proud of how knowledgeable he is, he should realize that there are many who know much more than he does. The arrogant person must know that whatever he owns that causes him to be arrogant will bear witness against him. When a deed is done to satisfy one's ego and have the people praise you, it becomes a demerit and doesn't benefit him one bit.

The Messenger of Allah (SAW) said: "Allah, glorified and exalted is he says, 'Pride is my cloak, and glory is my lower garment, so whoever contends with me regarding either one of them, I will torment him." - Muslim