On the sunken cost fallacy, there could be another, perhaps more sinister reason they won't sell nor invest in the team tucked away under Rule F.1.8. of the Premier League ownership rules.
If they have been investigated for tax evasion or money laundering, which I believe is what the Indian Directorate of Enforcement deals with, it would appear our overlords could be disqualified from owning the club should a promotion have been achieved.
(Rule F.1.10 states that they do not have to have been convicted for such an offence, only that it must be 'in the reasonable opinion of the board'- is it unreasonable to suggest it has happened if they have been investigated and subject to government sanctions?)
Promotion and subsequent disqualification would mean a cheaper sale than they would hope for (i.e. Abramovic to Boehly) or a dilution of their ownership (Dai at Reading)
It is likely that this would have been the case even before the court case became public knowledge, so perhaps we have our answer to why the investment was pulled after missing the playoffs on goal difference under JDT and now another lack of investment/not re-signing our best players this summer after being one goal away at Bramall Lane.
'The sanctions are no barrier to investment' we were repeatedly told. Maybe rule F.1.8 is.