It's a couple things:
1. Porn
2. Diet
When you fapping to nut any time you want over some porn, it changes your brain chemistry and tells you that you're satisfied even though it's artificial satisfaction. Porn creates a reward loop that reduces your aggression. Without it, you need to appease your appetites naturally and so your body does what it needs to do to give you the best shot at the reward (sending signals to produce testosterone, sperm, etc). Think about it this way: steroids is a shortcut to satisfying body image results but what the side affects? Your balls shrink... u start to grow t*ts... cause you replaced the system that tell your body to produce testosterone with a syringe and your body said "fukk it, my job being done for me." Before porn, men have to work to get off either through game, improving their health/looks etc. more and more dudes now is out of that game and satisfy themselves with quick releases.
With diet, we are ingesting the worst motherfukking shyt imaginable and it comes packaged conveniently and cheaply. I'm willing to bet that 99% of people on here (myself included) don't know where 90% of the stuff they're putting in their body comes from. Some of the shyt might be ok, but we don't know for sure... next time you eat or drink somthing out of a package, read the label, grab your smart phone and Google every ingredient you can't recognize and probably don't have any hope of pronouncing correctly. shyt is fukked up and people aren't awake to it and that's the bottom line...