It's an interesting question! I'd say the reasons are probably all of those!

Some have monumental egos, no doubt about that.

Some simply honestly believe these are laws in the sense that hey held and will hold forever (and since Newton did believe in God, he probably thought he was simply revealing the laws set down by his Creator).

And for some I think the words might simply sound nice! You have to call it something. In the case of the Central Dogma, since it was Crick who named it, I think it was mainly a case of making it memorable and being playful with words; he wasn't the type to call something by a dry name like others would, and I'm with him on that, we need to make science more interesting even when it comes to the names we give to things.