Selling through life

Why do we have to sell anything?
Including our views, beliefs, opinions and of course products?
When I say 'sell' I mean the efforts we undertake to exert undue influence on a transaction to work in our favour. Should we not just do our jobs and rest content in a job well done?
Isn't advertising a subtle form of psychological manipulation?
I know Katrina Kaif does not use Lux Beauty Bar. But still I stand to be influenced by the ad.
In this media infested world is there any such thing as free will?