Marketers are often charged with the task of getting people to change some kind of behavior. It could be to have you to buy something. But a monetary transaction is not always goal.
It might be to get you to eat healthier, stop smoking, drive your car safer, read more books, brush and floss or maybe prevent forest fires. The benefits from such changes in behavior are all quite obvious.
Then why are they still problems?
That's because just acknowledging and understanding a problem is not enough. If marketers want to change behavior then they must get people to change on their terms. And because the change was their own, they will feel stronger about practicing that new behavior.
This applies to marketers that sell stuff too. A person may know of the new widget x and understand what it does but that doesn't guarantee a sale. There must be something within that wants to buy widget x.
And the influence of friends is so often critical to bringing that to our attention.