Just go and do what must be done. Bugger his opinions.
Then move out.
Even dads have to grow up sometime.
if cannot then try argue with your grand dad lor...anyway, stop argueing with them lah, like me, my dad also dun bother much one, you argue, he will just say, shut up lah angel, so I changed my tactics, whenever i to my dad, I give him the solution first, talk nicely, somehow it works, he begin to see that I am begining to talk senses, like when i want to change my car, i told him that COE is rising, calculated the estimate cost if he do not renew a new car for me, when he sees the logics and facts, he agreed. He even praised me for making a smart move.
So, you see, all these middle ages Uncles and daddies need respect, dignity and pride, you praise them, support them, talk to them base on facts and figures like in boardroom, they will appreciate and better understand you ya
Like what Andrea Chanelle Chia and angel7030 said, you got to approach the situation with some tact.
Dad's apparent childish behaviour may stem from stress, or he might be emotionally stunted (read: mother damaged) or just using it as a ruse to "win" the argument. Maybe a combination.
Has his right upper limb neurological deficit been properly assessed? He might feel defeated and "useless", redundant because of his physical infirmity, compounded with the hovering failure from his failed investments, thus his thoughts that he is "better off dead". You need to bring him round somehow, and showing him love may be trying at first but it will pay off.
So buy him a beer or two at angel's pub, make it non-confrontational, and be sensitive and sincere about resolving issues. He needs to know it is not a personal attack and that he isn't a burden, that you want to do something positive, hopefully win-win for everyone.
Yes, us blokes can talk about feelings, but only after a few beers. C`mon, you can do it.
yo mate, yr sarong just dropped, after few beers, you guys can talk about feeling, while after a few glass of chivas, you guys can talk about being superman, with a few more, we gals can then join in.