When it comes to how much of their winnings golfers keep, it really varies depending on the tournament and the player. For example, in 2015 Tiger Woods won $1.8 million dollars at The Masters, but he only took home $1.26 million of that due to taxes and fees. In contrast, Jordan Spieth won $1.815 million at the same tournament and ended up with $1.485 million after everything was said and done - meaning he kept a larger percentage of his earnings.
Generally speaking, though, most golfers will take home around 60-70% of their total winnings after taxes and other fees are taken out. So if a player wins $1 million at a tournament, they can expect to pocket anywhere from $600,000 to $700,000 of that. Obviously this is still a significant amount of money, but it's important to remember that these athletes are also shelling out quite a bit in terms of travel expenses, caddy fees, etc., so their overall take-home pay isn't as high as one might think.