I think most of the reasons are obvious. Money, fame, and in this case to also push the theory of evolution.
Ok, let's unpack this, shall we?
Money: From where? Who is allegedly bankrolling the great dinosaur fraud?
Fame: Ok, without Googling, name the world's most famous paleontologist.
Without Googling, name the paleontologist who "discovered" the T-rex, the Stegosaurus, or the Pterodactyl.
Without Googling, name
any paleontologist.
Because the best I can come up with is Dr. Alan Grant, and he's the
fictional character from the
Jurassic Park series.
Push the theory of evolution: Circular reasoning, because now the question is why push the theory of evolution?
Money? From where?
Fame? Name a famous evolutionary biologist besides Darwin himself.
You haven't thought this through, have you?
There are those who oppose scripture, and would encourage anything that is against it. Pride is also an issue, as when most find out that they were wrong, they would choose to double down instead of correcting things.
Of course -- you think dinosaurs were fabricated
just to make your religion look bad... and
they're the ones with pride issues.
Of course there is Satan influencing most; he deceives the whole world, and the father of all lies. The understanding and belief of the majority is based on lies.
Of course -- everyone is deceived except you... and
they're the ones with the pride issues.