well, 61 was an achievement for Hemingway. he had long been self-destructive (literally), clinically depressed, severely alcoholic, guilt-ridden. that he lived to 61 was indeed heroic. it is impossible/futile to speculate if heavy drinking precipitated severe depression or whether the heavy drinking was a way of self-medicating. since Hemingway's father had committed suicide with a gun, he may have felt resigned, "fated" to emulate his father. we see in the early story "Indian Camp" a triangular relationship between father, son, suicide.

@JoyceCarolOates The quite serious head injuries from the two (!) African plane crashes plus the surveillance/harassment from the government (long dismissed but may well have actually been occurring) was in the mix, too.