Let's say you were the 2nd person to mine bitcoins besides Satoshi himself. Every time someone else mined bitcoins besides you and Satoshi you bought them.
There's no guarantee that they would sell to you.
You'd probably have about $500-$1000 into bitcoin by now... and you'd own like 5 million bitcoins... no one else would bother to mine them then, you'd own all the rest of the bitcoins besides Satoshi's who disappears in 2010 and then you disappear in 2011 with your 5 million, no one remembers what bitcoin is and you'd have a net worth of 0! yay
What would be the rationale behind doing that?
Even if you could someone acquire 5 million units of bitcoin, which is almost impossible, and disappear with it, it just makes the rest of the bitcoins more expensive.