Why are we so concerned about 1/2 of 1% (Golden Calf episode)

Question

We just read (in Parshat Ki Tisa) that the Levites punished the 3,000 men who took part in the golden calf episode. But 3,000 is only 1/2 of 1% of the 600,000 Israelite men who left Egypt. Why is the golden calf episode so important to our tradition if it involved such a tiny proportion of the people? Is there commentary on this?

Answer 1

The Ramban to Shemos 32:7 explains that there were multiple tiers of sinners in the golden calf episode, all of whom had different intentions of varying degrees of infraction, but that it was the majority of the nation that sinned:

אמר השם למשה כי עשו שתים רעות האחת כי שחת עמך וענין ההשחתה הריסת בנין... השני כי עשו עגל מסכה והשתחוו לו ויזבחו לו והנה העבירה הראשונה לא ידענה רק השם לבדו שהוא יודע תעלומות לב והשנית מעשה הזובחים החוטאים שבהם כאשר פירשתי והנה רוב העם חטאו במעשה העגל כי כן כתוב ויתפרקו כל העם את נזמי הזהב ולולי זה לא היה הכעס בכולם לכלותם והנה הנהרגים והנגפים מועטים כי ברובם היה החטא במחשבה רעה כמו שפירשתי

(translation mine) Hashem said to Moshe that they had done two wrongs, the first was a matter of [spiritual destruction] and the second was the making of the calf and bowing and sacrificing to it. The first is something that only Hashem knows its nature. The second was the sacrificing. And most of the nation sinned with the calf, as it is written "the entire nation took off their golden rings" and if not for that, Hashem would not have been upset at all of them to destroy them. Those killed and those struck in the plague were few, as most of them sinned intellectually, as I explained.

The "as I explained" refers to the Ramban's commentary to verses 1 and 4, where he explains that they did not actually think the calf was G-d, and they wanted a replacement leader with the disappearance of Moshe.

Answer 2

Many people beyond the 3000 killed by the Levi'im were guilty (and punished). Yoma 66b records two views:

It is stated: Rab and Levi are disputing in the matter. One said: Whosoever sacrificed and burned incense died by the sword; whosoever embraced and kissed [the calf] died the death [at the hands of Heaven]; whosoever rejoiced in his heart died of dropsy. The other said: He who had sinned before witnesses and after receiving warning, died by the sword; he who sinned before witnesses but without previous warning, by death; and he who sinned without witnesses and without previous warning, died of dropsy. (Soncino translation)

I found this passage via a note in the Stone chumash, which recorded only the latter view. Whether this means Chazal rule that way elsewhere, or that the editors of the chumash chose the one they liked better, I do not know.

Either way, though, way more than 3000 people were punished, and the transgression itself was major and very public. (I would think that it being right there at the foot of Har Sinai, so soon after matan torah, would also be relevant, but I don't have a source.)