I think you're not wrong in trying to make more money for your Dad, ...
I don't know how old the OP is and can make money, but the idea of investing with other people's money is a bad idea, let alone whether the money matters to them or not. If you can't make money yet, you are not qualified to teach anyone how to make money.
I totally agree with you on this very statement of yours about it not been a good idea about investing with other peoples money, not especially to mention a retirement benefit of an old man who ought to have start enjoying the fruit of his labour, living a good life, eating whatever he wants to and enjoying his last days, as in this mortar world nobody lives forever. However, it's left for his father to decide, as I'm sure he should be retired by now since O.P said he had just only 2 months.