We don't. We derive pleasure from harvesting game. A conscientious hunter's goal is to do that with as little pain and terror as possible.
The process itself is primal, and intrinsically validating for one who is unashamed of masculinity. To bring home the venison is akin to bringing home the bacon; it says to you "Yes, you have what it takes." It's affirming.
That said, it's not for everyone.
However, anyone who is unashamed of masculinity--and who is comfortable with himself and loves being a man, as I am and as I do--needs no validation or affirmation. He is himself his own validation and affirmation and his own standard of masculinity.
And, furthermore, the infliction of pain and fear--and, for that matter, hunting--is not intrinsic to masculinity.
And many of us men, who are unashamed of masculinity and in fact revel in it, are completely comfortable in setting our own standards and, already knowing that we have what it takes, need no further affirmation.
From what you have said, I infer that you also fall into this category. You set your own standards of what masculinity means and love your own masculinity and all that it means to be a man--as I do--so you do not need validation or affirmation. You are--as I am--your own affirmation and validation. Whether you hunt or not has nothing to do with it.