Imagine this:
- You're a mid 20s guy
- You have $600 to your name
- You have this overwhelming urge to play poker
- You go to the casino. There's everything from 1/3 NL to 5/5 PLO.
- "There's no point sitting at 1/3 NL with only 2 buyins. If I'm going to play a game I'm not rolled for, I might as well gamble with the big boys at 5/5 PLO"
- You sit down at 5/5 PLO with $600
- You play a 20/15 TAG style whilst most players are doing their 80/5 p-fish thing
- Within 2hrs you have an $1800 stack
- You get into a huge pot with 90% equity
- You desperately want to win. You're extremely nervous.
- You lose and you're down to $1200
- After some calculations you think to yourself "I would be on $2500 if I won that pot. I should've won. I was a 90% favourite"
- Even though you're $600 up, you still feel like you need to "chase your losses"
- You start loosening up to a 50/30 style
- You soon get stacked playing a hand that you should've folded preflop
- The next day you wake up broke and think "**** I could really have used that $1200"

This cycle happens over and over again... I feel like if I just had the bankroll to play 1/3 NL then none of this would ever happen. Should I take out a $5k loan?

Get two pieces of paper, head one of them with:

'- After some calculations you think to yourself "I would be on $2500 if I won that pot. I should've won. I was a 90% favourite" '

And the other with
'- Even though you're $600 up, you still feel like you need to "chase your losses" '

Dissect the logic in them in detail and in writing. Why do you think you should've won? (you should only most of the time in a large enough sample, so not really 'should've', for example.)
The second page will be meatier. Why you need to chase your losses, what will the outcome be if you don't, any faulty logic supporting your proposition.
These two ideas are the foundation for the whole problem. Dissect them, work out the correct logic and correct conclusion, then go over it repeatedly (especially when actually in the situation) until you really believe it and can act on it even under stress/distress.
obv don't take out a loan
gl

Imo don´t take loans, it usually makes people play more pressured, and overthink many situations that lead to playing worse.

Thank you for posting this OP. You put eloquently into words something I've been doing/feeling for years and it helped me spot a leak in my mental game. Now let's hope I have the wisdom to plug it.

I wouldn't take out a loan to play poker. It will just add more pressure, and unfortunately, it seems like your mental game is lacking to the point where you won't be able to play well. Past that, taking out a loan to play poker is generally a bad idea. Work hard in other aspects of your life and come back when you have a roll.

When you worked your stack up to $1800, why weren't you thinking 'oh I've been on the right side of variance here, if my edge is 10BB/hr (a v good winrate) I should only be on $660, this has been unfair on everyone else'.

We always analyse how good it would have been to win the flips we've lost and overlook all the run good we have had to get there in the first place (you can run well without being all in). You will eventually get to moments that you lose an all-in that you were favourite for. If you then proceed to spew off the rest of your stack, then you're a losing player and shouldn't be playing.

Also you need better bankroll management. If 100% of your bankroll is on the table, then of course losing a chunk of it is going to send you into mental hyperdrive. In PLO, the best in the world could play against a guy who's never played PLO before and if they're only 1 buy in deep there's a reasonable chance the reg goes broke. It's impossible to realise your edge playing like that (if you do have one). Run up a roll playing 25c/50c or something where the money doesn't mean so much, or save up a bigger bankroll before embarking on a trip to the casino. That way you've earnt the shot to play those games and will have a more thorough hand sample to say you're a winning player. Playing a TAG style preflop isn't enough to presume you will crush the game so hard you don't need to worry about bankroll.

PS don't get a loan. A future 'broke a**' version of yourself would want me to tell you that now rather than later

Some very good advice here. Thank you everyone who responded.

The good news is that I ran super hot this week playing mostly 1/3 NL and 1/3 PLO. Not only do I have a $2500 bankroll now, but I also put $1500 aside for an overseas holiday. So it looks like I won't be needing a loan after all.

Still, there is something I want to change about myself:
1) If I play well but get unlucky and lose, then I feel bad. I should be feeling proud of myself when this happens, since I know I won EV and made good decisions that will make me a long-term winning player.
2) If I play poorly but get lucky and win, then I feel good. I should be feeling ashamed about how badly I played, rather than just feeling good about results.

How do I tell my brain to stop being so results-oriented and so short-term money focussed?