Utd spent huge sums of money on transfers that were, in the main, rubbish.
Large transfer fees and huge wages - latterly because they had to in order to attract players to a generally misfiring team.
I'm certainly not defending the Glazers and the way they siphoned money out of the club would rankle with me if I supported them. As would the neglect of their stadium.
But I'd argue that a crazy transfer strategy (resulting in poor players - skill and mentality wise), coupled with very average managers have led to their failings more than the Glazers.