Question

speech on "vanity is expensive but useless"

Answer 1

dictionary describes vanity as 'excessive pride in one's appearance, qualities, abilities etc.It is extensive belief about one's attractiveness to others.' 
I say it is a exercise in futility. 'Beauty is skin deep' is an age old adage and rightly said. Beauty or pretty appearance doesn't stay forever and thinking one is superior because of it is a constant enemy of one's dignity. Nowadays more and more people glance in mirror at themselves and want to be 'fairest of them all'. Individuals' insecurities and low self worth makes them crave to fit in. They seek attention and approval of others and lose themselves in the process. 
Boasting about dressing in branded fashion trends, using app filters to enhance looks in pictures, obsessing over it getting maximum 'likes' etc have become expensive trends worldwide. Just to look pretty people are going to lengths. As it is said pride or 'hubris' is a deadly sin and should not overpower you or control your actions. One should try not let their lives revolve around approval of others and instead embrace and revel in one's unique individuality.