[Jagat]

>> everyone already knows what they need and where to get it.

You're overestimating people ability to know what they want, and moreso where to get it.

[erentz]

If they didn’t know they wanted it before an advertisement played on their psychology to make them feel they needed it, then they didn’t really want it.

And if they did know they wanted before the advertisement, then they’d go look for it at a store, online or otherwise, or in a catalogue, or so on.