Being VP is one heartbeat away from being President and it also assures you can have a presidential nomination for yourself later on if you want it (Dan Quayle being an obvious exception, of course). Rubio is full of sh**t, just like Obama was when he was talking about 2008 possibilities in 05 and 06. Oh, and did that hurt Barry's reputation, starting a presidential campaign after two years in the Senate?
The election of Barack Obama as President was a complete aberration and it would be foolish for any potential candidate make an attempt at replicating it.