Do you know what I mean?

Are you saying someone would use a powerful person for personal gain?

There is an English expression: to ride a man's coattails. This means a person would gain by supporting someone already in power without working for it themselves. Is that what you mean?

Used in a sentence:

Mr. Jones rode the coattails of Governor Smith to become the new health inspector.

Exactly what is meant by my coinage "hang on "
Yes, in our society (indeed in all societies) there are people who exploit the power or influence of the person in power, or having a lot of money, or of the dead person for personal gains. So, can I say ride the coattail of the man in power, ride the coattail of a moneybag, ride the coattail of a dead man?

You can really only use the coattail expression for a person [living], because a moneybag does not wear a coat, nor does a dead man!

Not even ...
Not even when used in a figurative way?

I think you could use the term even if the person is dead. Many people have continued to use the power of a person even after they are gone.

Sentence and example:

Elvis Presley impersonators still ride his coattail to make a living.

Well, that's true, but it only sounds right if you insert the word "still" as if to explicitly say to the reader, "...even though he's dead!"