The club had heaps of money from the Ferguson era so they didn't buy a championship team with no money. Much easier to build on that. Glaziers were billionaires and own a big sports franchise in the states. Don't forget billionaires get that way by not doing shifty business and probably have stored billions in other people's names eg family members.
Again much easier to build on Man U success than to where we came from:(
Currently, they have legit $4.7B and that's not with the sports assets MAn u which they paid 1.2 bil and don't know what the other team is worth.
So all together they would be worth close to 10 bil.