There is power in numbers. The combined power of a group is more than the sum of its individual members.
The little pool of water gains strength after it joins a lake. The lake in turn becomes stronger when it is fed by a river. The power of the ocean enters a river when it joins eventually. Power grows by grouping.
In the forest, animals move in packs and droves. We humans derive power from communities. Whether it is a mob, a random group, or an organised group, power lives and grows in it. Religion and politics thrive around organised communities. So also radical and extremist groups. Because in them resides enormous power that the group’s leaders can wield.
Power attracts. A group’s numbers grow much as a magnet pulls iron filings to itself