for me I have never invested , maybe cause I feel that I have to risk a big amount in order to make some good money
You dont even need to invest a big amount. Invest some of what you have because it is a profit in a long run and almost always be. Im not sure why people are avoiding clear profit like that even if it is just a small profit or even just some satoshi but profit is still a profit
You can always use your funds because you can divest them anytime. Of course everything has a risk even if you hold btc forever then that is a risk already because the price can go down alot but people trust btc will go up , the same as people trust the gambling site operator to hold their funds