It's forbidden even if you earn millions of dollars, this is called usury.

I have actually saved an amount of shell currency in a reserved savings at a rate of 40% for 30 days to double the quantity, and then after a month I will have given the opportunity for the shell currency to rise and increase in price so that I can sell nearly double what I bought for double the purchase price. Do you consider my plan poor? I would appreciate your advice. May God bless you. Thank you in advance.