Question

When driven by group cohesion,a decision is taken only to be lamented for later is called?

Answer 1

It is known as “Conformity pressure”.  For example, if a group member thinking that the other members are also like him/her gets into illegal business, the other members automatically fall in line because they wanted to be accepted in the group and they want to be in the group.  This leads to lots of heartache and problems.

Answer 2

The answer of your question "Pressure conformity"
The group cohesiveness is actually about a bond link between the  members of any social group. This could be with respect to one and another or you can say it as the whole group cohesion. The members of the group behaves according to the group norms and attitude also likely to be same So in order to remain in the group and match his criteria one can take decision under it's influence. The conformity have the ability to occur whether in presence of other or could occur alone.