Do you believe it's a good idea to persuade an elderly person about risky things considering that your senior dad is already 79 years old? What happens if the price of Bitcoin continues to fall? Given his age, are you certain it won't affect his health negatively? When inviting someone to invest in Bitcoin, you need to know what you're doing and whether it's safe for them.
For me it is a bad idea, I don't see any benefit for a 79 year old to invest in bitcoin, conversely, if bitcoin is volatile, it will shock his father. If he is a filial son, he should focus on his investments and buy things that his father likes, for an old man, they need time and joy, not money. If we want to give investment advice to others, we should choose the right audience.