One other way the Glazer's cost United success and money that never gets highlighted is in their terrible football business acumen. Here's a thread of examples.
1. Ander Herrera allowed to run down. 25 million player walks out the door for nothing. 25 million loss.
United sign Di Maria for 60 million knowing he's not keen on the move.
12 months later sold for 45 million. 15 Million loss
Alexis Sanchez cost around 10 million in agent fees and signing on fees. Over the course of his contract he cost around 50 million in wages according to one source. Plus another 9 million for him to go to Inter. A loss of around 70 million all in!