Theres a lot of ways to double your money, without risking it. But in order to double it you must be hardworking and smart.open a business where bitcoin can be use. Like an online store.
But opening a business is in fact a risky proposition, in fact most business in my county declare bankruptcy before their second year of being in place.
Business are a high risky, especially if you have no knowledge in the area that you will open this business.
Online stores sounds like a "zero costs" business because you don't have expenses since you will be working at home however you will have to advertise to sell and find costumers, so it's a big risky.
I think no one opens a business if they do not have knowledge on it. With $100,00 you can't be too dump to not protect your investment.