Just a point of clarity (because I read that at first as well), they spent tens of thousands of robux, which are at a generic level 100:$1. So not as crazy as it sounds, still an investment.
I think you need to stop assuming people know things like the value of Robux or what OBC is if you want to communicate with normal people about this stuff.
It doesn't seem surprising me they started playing at 7, and they were playing the game in 2008. I definitely recall the game taking off a good bit with little kids around that time. By like 2010 or so I knew of a ton of little kids who were at least aware of the game if they didn't play it themselves.