acting out of character? I am concerned that his changing behavior indicates a deterioration in mental health but I may well be over reacting. He used to be more focused on the long term and cautious or prudent. He no longer follows his diet, has also started smoking again and drinking but not driving, thankfully. Risky investments appeal to him now that wouldn't have a few years ago. He has no financial concerns, but could get some if he were to get into these risky investments. He seems to think he needs more money. I am really not sure what is the best category for this one.
I would watch to make sure no one is encouraging him to make risky financial moves like friends with stock tips or so called "financial advisors" who phone or send "get rich quick schemes" in mass produced mailings. Many financial advisors want to switch (churn) a seniors investments so they make quarterly commissions on these transactions.
If he has chose to play with a small part of his money, it might give him something to control and make him have something to live for. He should keep it to an amount he can "afford to lose" not risk his assets for the rest of his life.