Should a person follow what others are doing or should he find another way? There are a number of cognitive biases that may influence people to follow the example of others.
For example people can show the confirmation bias and support whatever ideas and beliefs they have already. If actions of other people don’t contradict one’s belief there would be no reason to change it. And even if there is a contradiction, due to the confirmation bias people tend to ignore it. But it may work like this after a person has adapted beliefs from other people. Before it happens other biases may help to adapt such beliefs without critical analysis.
The crowd may force a person to do something, as a result this person can get some opposed beliefs due to the reactance effect. Also in the case of the bandwagon effect people simply tend to copy actions done by other people. Individual persons may even understand that their beliefs or actions may be wrong, but due to the peer pressure and desire to please people from relevant groups they would act anyway.
Actually many cognitive biases which could work in the same way for different people may create a crowd with similar biases. Illusory correlation, halo effect, Forer (Barnum) effect, and availability heuristic among others can do this.
As a result we have a number of actions and beliefs, enforced by the crowd and our cognitive biases. Sometimes these actions and beliefs can be good and useful, for example rules from the traffic code can literally save your life. So if the crowd believe these rules are useful, it is a correct belief. To avoid beliefs with bad consequences you can check them as well as any actions the crowd tend to perform.
Beliefs should have a source, you can check its source and the logic how this belief was formed. An action can be checked by looking for hypotheses, which beliefs can lead to this action. You can also imagine and check hypotheses of probable consequences of the action. Regarding both actions and beliefs categories you can also check who could benefit from these. If you or the crowd can’t benefit from the action of the belief, they should be avoided.