Manipulation
"The bandwagon effect is the tendency for people to adopt certain behaviors, styles, or attitudes simply because others are doing so ... The bandwagon effect works through a self-reinforcing mechanism, and can spread quickly and on a large-scale [1] through a positive [ or negative ] feedback loop, whereby the more who are affected by it, the more likely other people are to be affected by it too." [https://en.wikipedia.org/w/index.php?title=Bandwagon_effect&oldid=1195195870]
"Some jurisdictions over the world restrict the publication of the results of opinion polls, especially during the period around an election, in order to prevent the possibly erroneous results from affecting voters' decisions." [https://en.wikipedia.org/w/index.php?title=Opinion_poll&oldid=1198106376]
[1] aka exponentially - which is hard to grasp for most of us. (emph. added)