If you build a sandbox, and populate it with kids, they will do the things kids do -- mimic things they see adults doing.
And so, invariably they build job simulators: https://m.youtube.com/watch?v=uq0orHycjHI&t=12m41s
Or just, you know, entire (pyramid scheme) corporations: https://m.youtube.com/watch?v=hE6jxjKPNZQ&t=6m35s