Numbers are of No Proof to Truth
Rabbi Moshe Ben-Chaim
We must not be impressed by people - be they masses, or an individual.
When Korach revolted, had the Jews said, "He (Korach) is right! He is a leader.", the Jews would have been guilty. And we see that Korach didn't die alone. Other followers met with his same fate. Today as well, if some great scholar tells us to perform palm reading, we positively declare that the act is Avodah Zara, regardless of the person's reputation. Such an act, the Rambam outlines in Hilchos Avodah Zarah, and is considered idol worship. Fortune tellers are forms of Avodah Zarah.
We find an area in the Torah informing us of a Navi Sheker, a false prophet. He can be the greatest Jew ever to have lived, but if he says something in Hashem's name falsely, he is put to death. We don't pay any attention to who he was. Similarly, an Eir Hanidachas, a city which wholly follow idols - is completely wiped out. If we say that when many Jews do something, it must be right, how could the Torah say to kill these people? Evidently, the Torah does not pay attention to how important a person is, or to how many people follow a specific act. If it is clearly prohibited, or punishable with death, then the penalty must be meted out. Again, if we see in our society today many Jews following an act such as wearing red bendels to guard against ayin harah, we don't care that thousands follow this false belief. (Tosefta Shabbos, Chap. 7 clearly prohibits this practice). The Rambam states clearly in the Yad Hachazaka, that individuals who write the names of Malachim, angels, on the mezuzah, they don't only lose a share in the world to come, but they take a command which incorporates the most fundamental of ideas, the Unity of G-d, and wrongly make it into a personal amulet to guard their physical bodies.
We must always consult the Rabbis and the Torah (not the masses) to determine what is considered Torah.