Owning just 21 Bitcoins makes you one in a million. In my opinion, this is enough to be quote-on-quote Bitcoin rich.
Check the
Distribution of bitcoin wealth by owner thread by Rpietila.
https://bitcointalk.org/index.php?topic=316297.0According to the latest stats published by him, some 349,000 people own Bitcoins (i.e more than
BTC1). Out of that number, some 14,000 own more than
BTC100. So owning 21 Bitcoins will not make you one in a million (if you take the total number of Bitcoiners).