No, the act of raising a kid itself gives people purpose, so it's not a pyramid scheme by any means, but let's not let facts come in the way of a zinger of a one-liner I guess?
You spend 20–40 years trying various things, living for yourself, finding nothing that sticks. Apparently being an idiot, but you’re just inexperienced. There’s some hole in your life. Then you have kids. Aha! It makes sense. Living for others! This is it! The irony being that now those people-you-live-for have to go through the same process, where 1/3 to half their life they spend in that apparently meaningless phase where they haven’t found their purpose yet.
This is totally void if you are the kind of person who cruised by and was happy without children but then the transition to having children made total sense as well.