I've got your point there, Indeed, those given links above are risky to try. Earning more in crypto is not just an easy way, those trading and gambling are very risky you need to manage it well because some of them get lose and failure in that kind of business.
I didn't try that site, I much preferred on investing and holding my crypto assets and wait for the right time when bullish will happens.
Without withdrawing fiat currency is depends on how you control your self not to withdraw into fiat.
There is no need to use any of the options given by the OP, many are not real options, he says that gambling is a way to multiply your bitcoin and while that can be a possibility if you are lucky you cannot really depend on your luck when it comes to your financial future, it is way better to have a strategy that you know has a real chance of making you money over the long term instead of trying to get easy short term profits.