I absolutely understand what you all mean but it's 0.01 BTC, we are not talking about lifelong savings. I'm also relatively relaxed because we're not in the bubble phase of the market just before the top, so if history repeats itself, it's unlikely to lose much money for anyone investing now.
That amount is not too large and will not be lost if you do not sell. But encouraging an 80 year old to invest or do something just for the money, I don't think it's a good idea. I also have an elderly father like you, and what I think he needs are days off and enjoying his old age. What they need now is the love of their children, health, and joy every day, not money. He will be happier, happier if you invest in bitcoin and make money from it, have a rich life, that's what he needs.