It's sad to look at how much btc is lost due to gambling, especially when btc was really low. If you consider it an investment, I suggest buying more btc to cover any you risk gambling, so you don't end up losing your investment. If you want to play with $100 usd, buy that much btc to offsite what you deposit at a casino. Then, if you win, you can either cash some out, or just add it to your btc investment.