The buyers don't want people smart enough to think for themselves.
The buyers don't want people who are too honest to BE bought.
The buyers don't want people are too personally wealthy.
The buyers don't want people who are too independent.
In a lot of cases (hopefully not all), you can substitute the word "establishment" for buyers,
and the same things will apply.
There, you have the reasons that Bloomberg didn't win the nomination... too wealthy, and probably also too independent.
There, you have the reasonS that Biden DID get it... he's "likable"... by every standard listed above.
There, you have the reasons that Trump was such a long-shot back in 2016... and why so
many of "the establishment" didn't like... and so many still don't... and also some of the
reasons that so many people voted for him, first in the primaries, then in the 2016 election.
(*I* was not one of them.)