Rivalries turning into friendships - how did you experience it?

First and foremost, I'm asking this here because it's tied to masculinity.

One thing that is absolutely beyond me is how rivalries can turn into friendships. It's highly prevalent in media, especially sports media, as well as media aimed at men in general (e.g. shounen manga), and is also present in real life, especially athletes, yet I cannot make sense of it.

So, men of Reddit, I want to know, what went through your head when you had a rival and decided "I like this asshole"?

Bear in mind, I'm approaching this from an outside perspective, as I was (thankfully) not raised to be "manly", and I never had a positive experience tied to competition, as such, what might be second nature to you is completely alien to me. If anything, I find it unrelatable at best, damaging at worst.

P.S. Why did I mention "damaging", you might ask? Below is my admittedly negative way to rationalize this concept - feel free to skip it, as I'm more interested in your answer to the question in the title.

P.P.S. My question is not something to be answered "some men are competitive, some aren't", as I already know that. I'm interested in what the competitive ones have to say.

It's a combination of:

1. Low self-esteem, which leaves the rivals oblivious to their intrinsic qualities, or they might be aware of them, but not care. Hence, they depend on external validation, and, because of this, they resort to competition to compensate for their low self-esteem, as being skilled at something is immediately apparent, and the praise for being skilled becomes their only source of validation, which, as mentioned earlier, is vital to them because of their low self-esteem.

2. A warped worldview where extrinsic qualities like skill matter more than intrinsic qualities, which might also be the reason for their low self-esteem. This is why they prefer being with an unpleasant, yet skilled person, in order to keep them "sharp", as opposed to a friendly person who is supportive but lacks skill.

3. The "suspension bridge" effect. They are so addicted to emotional intensity that they cannot quite distinguish good emotions from bad ones. Or, at worst, prefer negative emotions to positive ones because of the intensity. This leads to liking the rival because they are the source of said intensity.