Whether a need is valid depends not only on whether enough people are willing to change their actions in response to it, but also on whether it truly satisfies each individual in the group—clearly or vaguely—in some conception they hold of themselves and of the collective.
In essence, human needs are a seeking of the good.
And seeking the good divides into what one believes good for oneself and what one believes good for the collective. Some place the self above the collective; others, the collective above the self.
To persuade the collective or the individual is to convince them that a new product or service will make them stronger, or shield them from weakness—whether in themselves or within the group.