Learn English – n idiom/proverb in English to denote unfair discrimination

In English, we have the infamous know-it-all: one who knows everything; hence, a person who makes pretension to great knowledge, especially one whose didactic conversational habit conspicuously reveals his belief that he has superior knowledge on many subjects; a wiseacre; a know-all; -- usually ironical. [Colloq. & pejorative] Note: the use of this term implies that the speaker disapproves of this behavior, and may think that it is unjustified.

**know all: someone who seems to know everything and annoys other people by showing how clever they are.

No one likes him because he's such a know-all.

smarty-pants is an older idiom, for one who is obnoxiously self-assertive and arrogant, as is weisenheimer.

There is the Jerkass, who might say something like, "Sometimes I park in handicapped spaces while handicapped people make handicapped faces. I'm an asshole!" (— Denis Leary, Asshole) but this is more trope or jargon.

And, as StoneyB has kindly reminded me, there is the loudmouth:

Be loquacious, often noisily or boastfully; someone who talks too much or too loudly, esp. in an offensive or stupid way

*Harvard Square: Know-it-all capital of the universe. * - Universal Hub.

This too shall pass. It's appropriate both for the impermanence of good things and bad --there's a fable that a king asked his wise men to give him something that would cheer him up when he was sad, humble him when he was proud, comfort him when he was mournful, and calm him when he was agitated. After much deliberation, they gave him a ring with those four words engraved upon it.

For your particular use case, there's also the saying "the bigger they are, the harder they fall," which is specifically used for predicting the downfall of the high and mighty.