What the “customers” bought -
1. Influence, should a US policy or regulatory issue come up.
2. Protection, to guard against the above coming up.
In some ways the US Govt abroad works like a protection racket. It blanket threatens everyone with, for instance, IRS money transfer and bank account reporting for anyone holding assets in the US (a “US Person”).
A lot of Chinese “entities” want to move funds to the US (capital flight). They would rather not be hassled in this.
Just one aspect.
That’s the reason they hate Trump so much and the reason why they are making political prisoners out of people who strolled through the Capitol Building on J6. Trump and those prisoners threaten the racket.