I honestly have never heard the end of the song or have never remembered it lol.

This song is widespread not because of the end but rather the beginning.

I'd say people tune out even after the second line because they're already now into the thing they are doing.

What I mean by this is I imagine this song being so big at events like parties and weddings. And it just is like a lubricant that allows people to get into the present mood and appreciate what's happening. That's what I see as the

substance

of this song.