To Become A Dragon

In Chinese mythology there is a Myth where carps swim through the Yellow river. It's a hard and long journey, but if they leap the falls of the Yellow River and make it to the Dragon Gate they will transform into a dragon.
(this motif was meant to symbolizes success in the civil service examinations)


In One Piece there is one very famous dragon, named Monkey D. Dragon.
But there's also a Carp. Monkey D. Garp.

I believe Oda meant to say something by this.

In my opinion he meant that Monkey D. Dragon has climmed up like the carps do and finished at the top and turned into a dragon by doing what he believes is good and being the most important person in the Revolutionary Army. I believe Luffy will turn into a dragon as well "figuratively speaking".

But why isn't Monkey D. Garp a dragon?
I know he's a Vice Admiral and that's pretty good, but to become a dragon, you have to be better than good, you must be great and make your dreams come true. Vice Admiral isn't someone's dream, even Coby dreams of being an Admiral. I think Garp isn't forfilling his dream by being a Vice Admiral and he has regrets about it (i.e. regrets of never becoming an admiral) That's why he is a Carp

So what do you think?
Any other reasons why Garp is a carp?