Who is power gained by in a democracy?

in a democracy power is gained by the people who think most simalarly or the majority of people

However in todays world peoples opinons may be constantly influenced by the mass information available thru many outlets. This would mean that if a person or entity has the capabilties to mass influence the citizens of the democracy they can then direct the thuoght so their ideas are the majority opinion

This is exactly what is happening in the united states today with many mass media, entertainment industry, political parties trying to make their beliefs that of the majority. Most lik;ly for their own benifit not for the benifit of the majority