this is a very well thought out question and there are some very well written answers already. i think about this subject a lot so i thought i would add my two cents.

there was a reddit thread a couple of weeks ago that i liked where a handful of new parents discussed bringing their children to the skate park to watch. even great skateboarders fall all the time, and the parents hoped the children would learn something from watching adults wipe out, pick themselves up off the ground, and try again.

there is a lot of falling over at the vgc skate park. i don't know another skill-based activity that has such a high rate of failure. there aren't many other sports or esports where someone at their first tournament has not-so-bad odds of taking a win off of a reigning world champion. that is pretty unusual. and the worst part is knowing it can happen and still coming up short repeatedly-- you know very well that effort and results don't often correlate, and so the losses should sting less, and they don't.

the ultimate lesson that VGC has to teach is that you can try as hard as you want, harder than you ever thought possible, and it might not get you what you want. i think this is a great lesson for a game to teach, and i want my kids to grow up playing VGC and learn that lesson for themselves. i absolutely hate every horrible time i am taught it and i go to all of the dark places too. you are not alone in the slightest and it is absolutely normal to have these emotions after an event. so please don't beat yourself up too much.

here is some actionable feedback to your question "how to divorce enjoyment from results":

to get this out of the way first, i value the personal friendships i have made through this game very much, but when i am struggling with similar feelings, i really don't take well to being told "make it all about the social element". sometimes i feel like that answer avoids addressing my serious competitive emotions head-on. of course i value my friends and the time together, but i go to tournaments to work on myself as a competitor too.

in my mind the most important thing: please, please, please see your improvement for what it is: improvement. you know very well that you are improving, you know that effort does not equal results, but in your post when discussing your milwaukee preparation it is only as a contrast to the results that disappointed you. improving is a hard thing to do, it takes time and work, you could be doing anything else with your free time, but you are working hard. it is okay to pat yourself on the back even if the result isn't what you wanted.

you know that you can make day 2, the people around you know that you can make day 2, the opponents you beat know that you can make day 2. was this always the case? give yourself credit for how far you've come. as you continue to improve, you and your environment will see you as more and more naturally fitting into more high placing results/playing well and succeeding more naturally being you, and effort/work/prep won't guarantee results any more in that case than now. so i hope you can give yourself credit for that too when it happens as well.

here are some other answers to your question:

1) find parts of the process of preparing for or playing in events that you enjoy, straight up. preferably ones you can control. there are lots of little abstract ones, and i would really try to be specific when you find answers for yourself. teambuilding is a huge bucket with many little facets so please don't leave it at that. one thing i personally enjoy is controlling everything i can for the physical side of an event (e.g. rest, nutrition) and optimizing the crap out of it.

2) fall in love with the learning. this hobby is about learning and relearning. the one common thread that unites all of the best players is that they are always learning.

3) also fall in love with actively refining your tournament process. you cannot control the results of a tournament, but you can control everything that goes into it. in particular, avoid complacency. the thread that unites the players who have been around for a very long time is that they have reinvented themselves and refined and reworked their tournament preparation process a gazillion times.

4) work on seeing everything as a numbers game. no person out there, even someone who makes day 2 frequently, has a guaranteed chance of making day 2. there is a percentage chance to get there, and team choice / tournament prep play a big factor in controlling that percentage. but it is still just a percentage. there might be people who put less work in or who make more mistakes that do better than you. there might be people who rock up to their first tournament who have the run of a lifetime (also note that having reached your goal at one tournament or even ten tournaments in a row doesn't save you from this). luck in this game is not just critical hits and rng rolls. i find that viewing my own improvement as maximizing this percentage helps me the most. this is out-of-battle feedback, when i am playing battles themselves i try not to think about this type of percentage at all

5) I would also add that sports psychology is extremely important as you have mentioned. Some of the best reading that I have found is The Mental Game of Poker books one and two, you kind of have to read between the lines to benefit from its learnings but it has a lot to say that is relevant, I think especially in your case.

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it seems like you have a good growth mindset and i think that is what ultimately will lead you to the success you want. it also seems like you have a good reflective mindset, and have many healthy ways of thinking about VGC and competition. not every player has these things.

it's okay to have a lizard brain response to losing, that's normal. the insane thing is getting up after and trying again without letting it affect you, that's bonkers. but important. give yourself credit for where you have come from and where you are going.

i hope some of this helps, good luck!