One thing I remember reading that really stuck with me - most people externalize failure and internalize success. Meaning, when things go wrong, they point to external factors. When things go right, they credit their own skill and ability.
The opposite way is to externalize success and internalize failure - that means claiming responsibility for it whenever you don't get desired results, but being very skeptical of your successes and looking for where external factors broke your way so you don't get too high on yourself.
Turns out, externalizing failure/internalizing success makes you much happier but much less able to produce results.
Whereas internalizing failure/externalizing success makes you much less happy but much more able to deliver results.
Now note, this only applies in cases where your incentives come from producing results, as opposed to convincing other people you did well. That's the trouble with middle management and with politics - you win by convincing people you're doing a good job, more than actually doing a good job. That's very conducive to blaming external conditions for everything going wrong, and claiming personal success for everything that went right... which is much less conducive to results.
Nasty, huh? Actually that's why self-employment/entrepreneurship is so cool - we get paid for results, not for convincing anyone we're doing well in spite of the results. Thus, while it's still hard to claim every failure as your own and be skeptical of the successes, we do get compensated better for it.
I'm not sure of your definition of "most people" but how do you square this with the impostor syndrome that is reported to be widespread among highly skilled people? It's the exact opposite of what you claim as the default psychology.
When you succeed, you're on top of the world and can do no wrong. When you fail, you're a loser who can do nothing right.
"Wow, I really screwed the pooch there. It's going to take a while for me to live this one down. I better get to work."
"Wow, I really screwed the pooch there. I'm worthless and I can't do anything right. I should go drink."
One of those, I think, is a healthy way of accepting responsibility for failure. The other is not.
The same, really, goes on the upside.
I was making a shoot-from-the-hip guess. The difference between the two approaches which you mentioned is a correct sense of proportion. Of course, the same applies to the other ways in which one internalizes/externalizes both success and failure.
I mean, proportion has something to do with how publicly and how strongly you repent for your mistakes, but I don't see any case where it is in your best interest to accept that you are worthless.
To be clear, I can see cases where it may be in other people's best interest to give up on you, but I don't see any case where it's in your own interest to give up on yourself.
So you're speaking from experience. Have an upvote.
I've started my own business, too. I commiserate.