Courts - it would take someone better at finances than I to explain it better....but I understand it is how they get the money for these big transfers - so they borrow large amounts of money leveraged against the value (and future tv revenues) of the club. THE CLUB is then liable for the debt (not the owners)....and the club pays it back. Meanwhile they enjoy the fruits of the revenues. Something like that.
Maybe this helps better than I am explaining it:
Are Manchester United in debt?
Manchester United are in debt and the club's net debt as of
September 24, 2019 was £203.6 million ($254m), down from £301.7m ($373m) on the previous year.
They did, however, announce record revenues of £627.1m ($782m) and an operating profit of £50m ($62m) for 2019, with the club "committed to winning trophies".
The club had been debt-free until 2005, but debt has risen and fallen since then, reaching a peak of nearly £778m in 2010.
Why are Manchester United in debt?
Manchester United's colossal debt is the result of the takeover of the club by the Glazer family in 2005.
The Glazer takeover of the Premier League giants was controversial because it loaded £525m of debt onto the club - through loans secured against its assets - in a move known as a 'leveraged buyout'.
Prior to the purchase, Manchester United had been debt free.
A refinancing of the debt occurred in 2010 when it had risen to over three-quarters-of-a billion pounds.