Most of what I've seen is that once "newness" of the voice and image fades, the actor/singer/media personality must attempt progressively more and more extreme things to remain in the spotlight (and in the money).

At least that's what their marketing people tell them...

Ecclesiastes 7:10-12

"Whoever loves money never has money enough;
whoever loves wealth is never satisfied with his income.
This, too, is meaningless.

As good increase, so do those who consume them.
And what benefit are they to the owner,
except to feast his eyes on them?

The sleep of a laborer is sweet,
whether he eats little or much,
but the abundance of a rich man permits him no sleep."