You may not have known this, but men have insecurities too. In fact, every single person in the world does. However, not everybody deals with them in the same way. Some people cannot stop talking about them, and it can get really repetitive and obsessive. Some people go to therapy to face them — probably the healthiest route. Then there are many people who try to overcompensate for them, and it can be so cringe to be around those people. It's like they're putting on a show for you, and you know very well that it's fake, but you have to try to go along with it anyway.
This Reddit thread showcases some of the most obvious ways men try to hide their insecurities, many of these behaviors are probably very familiar to you.