For 1 Bitcoin to be worth $1,000,000, the total market cap of Bitcoin would have to be $21 trillion dollars. What are the odds of this happening?

For reference, the amount of physical $dollars and coins in circulation are around $1.2 trillion. The global M2 money supply of all currencies are around $45 trillion. The market cap of all mined gold is around $7 trillion.

Will 1 Bitcoin be worth a million dollars? Half a million? Thoughts?