To be fair, the Board has been very open about this and regularly updates the fans on the reasons for our losses (from lack of league sponsorship, to changes in prize money to having no Rangers in the top flight etc.). The reason we know of the large losses is because of that transparency.
Utd. spend a comparatively huge amount of money on young players on long contracts that we can't afford. However, when they have the chance to sell one on, most of the fee goes to pay off the millions in debt they still owe. While they had fans that paid off their bank debt, the debt wasn't cleared - just moved to more favourable terms. From memory, they had close to 4 million taken over by benefactors - an amount that would have put us back in administration.
Plus, of course, for all the great young players they are bringing through, we still manage to stay ahead of them in terms of league position.