This bet doesn't make very much sense. If pirate does default, you're out whatever you had on the line. If he doesn't default, that means 500k coins will have been disbursed before you can win the bet; by that time supply pressure in the market will mean the price of bitcoin will drop precipitously. You may win 5k or 10k coins but they won't be worth anywhere near what they are now.
If you were smart you would sell the coins you have now, take the money, and reinvest when the price collapses. You'd probably end up with more that way.
I'm uber-long bitcoin so current price volatility is a non-issue. Bitcoins are bitcoins baby!