A seemingly routine and joyous wedding celebration actually serves as the cover for a calculated plot of deception. Laban organizes a massive public event, a practice that reflects ancient wedding customs and later inspired the traditional seven days of celebration for a bride and groom [שטיינזלץ, רד״ק, פרדס יוסף]. However, the sequence of events reveals a darker motive. Laban first gathers the townsfolk to consult and finalize their secret plot, and only after the scheme is firmly in place does the actual celebration begin [העמק דבר].
The primary approach among commentators is that the feast was heavily centered around wine. Laban's main objective was to intoxicate Jacob, dulling his senses so he would not realize that Leah had been substituted for Rachel. The truth of the bride's identity would only become apparent the following morning once the effects of the alcohol had faded [תולדות יצחק, הדר זקנים, דעת זקנים, קונטרס חיבה יתירה].
Laban's decision to invite the entire town, rather than just close family and friends, was a multi-layered strategy. First, the massive public presence was designed to lull Jacob into a false sense of security. Jacob would never suspect Laban of pulling off such a massive fraud in plain sight, and thus would not scrutinize his bride [מלבי״ם, שפתי כהן]. Second, Laban anticipated the aftermath. He knew that once Jacob discovered the truth, he would be too deeply embarrassed to publicly divorce Leah after the entire town had just celebrated their union [מלבי״ם, ביאור יש״ר]. Furthermore, by involving all the locals, Laban made them accomplices, ensuring no one would leak the secret to Jacob [אלשיך]. He also needed their collective voice to back up his claim the next morning that local custom forbade marrying off a younger daughter before the older one [מלבי״ם, אלשיך].
The mass invitation was also a masterful legal maneuver. Laban anticipated that Jacob might try to annul the marriage in the local court on the grounds of a fraudulent transaction. By feeding the entire town, Laban effectively bribed them, disqualifying every local from serving as a judge in the matter since they had derived personal benefit from his feast. Forced to seek a court in another city, Jacob would be delayed long enough to eventually accept the situation [חתם סופר]. To secure the town's cooperation in the first place, Laban convinced them that Jacob's presence brought them blessing and water, and that trapping him would secure his labor for another seven years. Taking no chances, Laban demanded collateral from the townsfolk to guarantee their silence. He then deceitfully sold their garments to fund the wine and meat for the feast, swindling his own neighbors in the process.
As the wedding progressed, the guests sang the word "Hilula," a subtle hint meaning "It is Leah," which Jacob simply mistook for a standard song of praise. To complete the trap, young girls were sent to extinguish the candles under the pretext of modesty, plunging the room into absolute darkness so Jacob could not see the deception [צאינה וראינה, שפתי כהן]. The ultimate proof that this grand event was orchestrated purely for deceit lies in Jacob's subsequent marriage to Rachel. When he finally married the woman he loved, no feast was recorded. There was no need for public spectacle, drunkenness, or elaborate tricks, because Jacob loved her and there was never any risk that he would want to send her away [ביאור יש״ר, הדר זקנים, דעת זקנים, שפתי כהן].