People like this don't understand the term 'save for a rainy day' because to them their enjoyment comes first.
The problem is there is no convincing such people, only life can teach them a lesson that's if they will ever learn.
You can only keep advising him as a friend but the rest is up to him to figure out.
Some people have the mentality that they will always have money, so they don't care about saving for the future. They fail to understand that a time will come when they might not have the strength or opportunity to earn money. Each time I see elderly people engage in manual jobs, I am reminded that a time will come when I need to rest instead of engaging in a full-time job. And the means of retiring at the right time is to save and invest for the future.
You can only advise a grown-up man and cannot force him to make a decision. Life is a choice and an adult has the right to choose what he wants. Your friend should bear the repercussions of his action alone but you can help him if you also join him in lavishing his money. I don't lend money to such people because they might not be able to pay back since they don't have an adequate financial plan that guides their spending.