
I did see a bunch of "I'll become a better person, you'll see" type stories, but it's usually:
MC gets transmigrated/reincarnated and doesn't want to follow predecessors path
-succeeds and amazes everyone around them
-fails spectacularly but endears everyone all the same
I think I remember seeing a story with a similar setting, but in an ancient type of story.
In a harem, a lady's child died, she loses the favor of the emperor, her sister claims the spot of the most favored concubine while she dies alone in prison, vowing revenge. She realized that her sister whom she loved is actually someone who would backstab her, and the man she loved doesn't love her. Upon coming back, she is a little like this main character, but does not bide her time - she goes head-to-head with the venomous snakes in her life and manages to win over some allies. I just can't recall the title because it's been so long since I've read it and I got frustrated waiting for updates and coming back only to realize I don't know what's going on anymore.
Found it! "Princess Wei Yang"! Man, I loved that story when I first read it...
And there's some other similar ones as well, around the recommendations area, but then, based on their reviews and ratings, it's a hit or miss...
And most of them are transmigrated modern women, not people who went back in time, so technically the original person didn't learn anything but that someone else had to step in and fight. Although there appear to be a few here and there who are actually MCs that went back in time.
It's setting is cliche, but these revenge-type plots work so well. I admittedly got hooked after reading only 5 chapters. It's the usual: ptiiful MC goes back in time as a "better" person and faces her greedy mother and her jealous stepsister who were previously the ones who caused her tremendous pain.
She doesn't go all out and declare war, no no, she bides her time and doesn't act aggressive - like a calm pool of water with its murky depths concealing the turmoil below.
Instead, with a gentle smile and a perfect attitude, she watches everything carefully, and so far, the jealous stepsister has sabotaged herself without so much movement from the MC, and the cousin is the only one she "amicably" dealt with so far.