I've always loved playing games competitively. I vividly remember going through the move list for Tekken 3 and finding out the most abusable moves, the ones hardest to block. And then I'd try and learn how to counter them. In Tony Hawk's Pro Skater 2, me and a bunch of dear childhood friends would get good enough that our games would boil down to who'd fall first. The game mode we played had a time limit, but as long as you were doing a continous trick, the game would continue. So we learned to keep grinding around the map for several minutes over the actual time limit. Fall once - be the first to fall - and you'd lose all your score and the game would be over for you.
Because I've always played games with a competitive mindset, I've usually ended up fairly good in them. Back in SWAT 4 and later in Insurgency, which are first person shooters without a matchmaker to match equally skilled opponents together, I have been sorely disappointed when I wasn't the first and best in every match. Having a positive kill-death ratio was hardly enough; In public games, I wanted to be breaking my own records, going 10:1 and above. Right now I play PUBG and Overwatch, doing good in the former and fairly well in the latter.
At the same time, I'm very far off from someone who could play these games at a professional level. The difference between the top 10% and the top 1% is huge, but the difference between top 1% and top 0.1% is even bigger. I'm 27 now, working as a tech lead in a small company, with a wife and a house filled with dogs and cats. For all intents and purposes, I think it's fair to say that by now, I've already peaked in my gaming skills and will not be seeing any dramatic gains. If that ever even was the goal, it is now safe to say that I will never be playing at a professional skill-level.
Time is, as it often is, the problem. The better you are at something, the more work you need to do to keep improving at it. When starting a new video game, most people will rank at roughly where they've also ranked in previous games. By playing the game, they'll slowly improve, but rarely is it very dramatic improvement and often they'll hit a wall pretty soon. In PUBG, I recall my very first game. I ended up 2nd or 3rd, with half a dozen kills. For a little time, I had a very good K/D ratio and so forth, but soon my winrates fell to the average as the matchmaker kicked in. In Overwatch, my season highs have only gotten slightly better since my first season. In my first season, at a scale of 0 to 5000, I reached 2900. Since then, my career high has been hardly higher at a mere 3250. Most of the time I spend somewhere between 2800 and 3200.
The gains are easier to see with a smaller time investment in things where you are the only factor. If you go climbing or bouldering twice a week, you'll improve for decently long before hitting a wall. If you go snowboarding twice a week, you'll again improve for a pretty good time before hitting a wall. With video games, it's a little bit different in that everyone else is also improving. You can only increase your relative rating compared to other players if you keep improving faster than they are improving. This means that twice a week is nowhere near enough. You need to spend some serious time to keep improving in a video game at a pace faster than the other players. And the higher in the ratings you are, the harder it is to improve at all. So you can even get lower in rating while playing if you aren't playing enough. But not many would get worse at riding a bike just because they only rode it once a week for a few months.
All this may beg the question; why bother, then? If I reached my peak ten years ago, why do I bother playing with improvement and competition in mind? To that, I can say two things; first, the very act of working out ways to keep on improving brings its own satisfaction. It's also something that translates to a lot of other things in life. Analyzing your own performance - and your own emotions and opinions - is a skill that you can compare to no one else but to yourself. It's a skill you can keep on honing to the end of the line.
Secondly.. Win or lose, there's no thrill quite alike the one that comes from competition.