Is seeking praise and flattery for one's beauty, and being keen on it, considered a sin? What is the jurisprudential and psychological explanation for this condition and how can it be treated?

It is not for men to be excessive in adorning themselves, for it is a fleeting world, and everything that rises from it will fall. Moreover, attachment to adornment indicates an emptiness of the heart from preoccupation with loftier matters. The Arabs used to praise a man for his ruggedness, not for his beauty. Indeed, Omar ibn Al-Khattab, may Allah be pleased with him, encouraged wearing coarse clothes and abandoning luxury and the attire of the non-Arabs.