Sell, pay your taxes call it quits.
why would you he quit bitcoin its still rising its like he has a property in a tourism area.keeps rising all the time
May be he would not like to take more risk now as he has make a huge amount of money and should sustain easily for the next few years and may be what OP can do is withdraw 50 % of the money to be on safer side and invest the rest in other coins to get returns.