If I were John I would not do it.I know that in gambling there is a high risk of losing any amount of money and trying to recover the price chance with gambling would be extremely risky.You have to have a lot of guts to do this and personally I dont.I would wait for better days regarding to bitcoin price as a solution.
And I would gamble the same way despite the value. It's interesting that most people when they use cryptocurrencies they still see it through fiat. They put in 0.1 BTC and all they see is 900 USD or something. When it goes up or down they change their betting strategy. I never do. I play with a percentage of my portfolio and when I have 0.1 BTC on a casino I divide it into as many parts as I need. Usually the smallest possible so I can keep playing for a long time. If it goes down in value i will still have as many parts of bitcoin as I had.