You stated Barcelona in both your examples.
If you are in £600k in debt in a £1m house and earning £200k a year it is sustainable and lot better than someone in no debt with a £30k house in Bacup on £18 k a year, who can't afford to maintain their dilapidated back to back, so it is all relative.
The PL clubs are worth far more than their debts which get paid off when they are sold to the next owner.
but its not sustainable it keeps growing and growing
if you are using your assets to maintain a level that in the end the banks will own more of your club than you.
investment and return ? manchester city owners knew it was a good business deal buying manchester city
but clubs like united and barcelona that run the debt to a point of no return make no sense
manchester city valued is around £2.5billion and turn over of around £500million a season
manchester united is valued not much more at £3billion and around the same revenue a season but have a big debt hanging around, so who is the best run club or have a better future ?
at the rate of growth and repayments percentages or re-mortgaging the debt is a never ending story
it has to stop at some point when the banks call in the debt and say enough is enough it will end up a fire sale