I feel like if I invest half the amount in Bitcoin for a year after receiving his retirement allowance, I might be able to hand over more money to my dad at the end of the year.
Hope I get proper advice from you.
That's a big gamble imo. What if bitcoin goes down and recovers after 4-5 years? What's your father going to think about this? Don't even do anything with that money unless you inform your father first anyway. That alone will cause lots of problems even if you make money in the end. Your father will never trust your judgement again. That thought is wrong on so many levels, I would rather forget about it quickly. Focus on your job or school or whatever responsibility you have nowadays. Stop thinking about somebody else's money. Make your own money and invest it in whatever you like.