Bitcoins Have become an awesome mode of payment in today's life, but how will people know about it without advertising? It's a known thing that to get more consumers, you need to advertise your product, similarly btc needs some more advertising, especially in places where btc is still used rarely
Since there is no central institution to profit from such advertisement, since everybody would profit from it partialy - weather they invested in advertisement or not.
But rest assured - bitcoin with it's structure and constantly progressing services will make public and followers for themselves.