What strikes me is when the clients know this to be true, but don't actually care. They have a budget and they need to spend it! Looking forward to the day when the market catches up to them.
Also remember clients also have their own bosses, board of directors, investors and supervisors to answer to.
It seems with Palantir it worked well with CIA. If you ever sold anything to Uncle Sam, you know he loves to pay lots of money and then pretty often it ends up not being used or forgotten. Guess they tried that with a few big companies but found out that Coca-Cola is not as careless with its budget as Uncle Sam, and \had a hard time convincing them to just throw away tens of millions on some analytics thing.
And, if it fails, political cover.
People bring in consultants for one of two possible outcomes:
1) Rubber stamp a preconceived conclusion or idea;
2) Test out an idea and take the hit if it fails.
Basically, they are there to ensure a win-win scenario for the commissioning member(s) of management.
How do you both take credit when you succeed and avoid blame when you fail?
You take an action that's easy to justify by external validity factors. If you succeed, you made the call, you take the credit. If you fail, you justify it using external validity factors ("they're one of SV's most valued companies! they only hire Stanford graduates!") to indicate there's no way anyone else could have done better.
[1] NMP: Not My Problem
[2] CYA: Cover Your Ass
[3] OPM: Other Peoples' Money
[4] Profit!