$100,000 is really a big amount of money. If i were you, i will invest half of the money into gambling site or something that have a good prospect and the rest of the money i use it for trading and gambling. I'm sure i can make that money growth with my skills.
Its is really a big money and you could make many investments on that amount but OP mentioned on how to double it safely then its really impossible because all investments have do risk on losing some of your money which it really needs effort and a deep research before you invest into a certain thing.As you said investing on gambling sites or in the house is good though but dont forget on the risk.