@muiris I'll give a different perspective from the rest of the comments:
He's old, I know how hard it is to find motivation to 'go further ' and I'm sure he can pay it back, maybe this is his way of working harder, giving purpose to life(?) (we all know its bad), so how about this...
Ikaw mag influence where he can take those money, dont dictate just maybe always have it as a topic whenever you guys are talking, influence him to spend it to become a shareholder ng blue chip companies or other potential investment youve carefully studied.
Just don't mimic his ways when you grow old...
I gave this perspective kasi i know alot of old people who has it all BUT the drive to live longer.