I to still don't get it. They could pocket billions in a short space of time. 4b divided by 30m is 133 years. Rough figures obviously but unless I'm missing something it is a bit confusing
It's incredibly easy to understand, you're looking at this backwards, the goal isn't to just get 4billion in which your correct would take all the years, why do you need 4bil, what are you gonna buy a giga yacht the size of the moon?
The club is worth around 4x times what they "paid" for it in 2003, so it's not how long the club would take to pay you the full value of what it's worth currently in another 20 years it might be worth twice as much again, then sell it. Also their dad technically only spent 190m, they are 20m to the good every year but they can sell at any point for multiples of what the original purchase price.
To put it into perspective, Newcastle sold for 305m, a club that has yo-yo'd with relegation for the last decade, even it United utterly imploded in the next few decades, they would sell and walk away with double "their" money + whatever they took out in the interim.