“And we were in our own sight as grasshoppers, and so we were in their seight” Bamidbar 13:33
A lesson can be learnt from the mistake of the spies, as brought down by the Kotzker Rebbe (Otzer Chaim), that it should not bother a person how others view him.
A person who worries about how others view him will have no peace of mind, with constant anxiety.
Self esteem should not be dependant on others, and a positive self image is vital.