The brain continues developing until around 25, especially the prefrontal cortex. "The development of the prefrontal cortex of the frontal lobe allows us to process the pros and cons of a decision before it is made. “It lets us to do things most animals cannot,” explains Dr. Stanislaus. “Decision making, logical thinking, reasoning — all of those things happen because of the frontal lobe.”
Perhaps Anon also became able to afford/figured out how to sleep, eat, drink alcohol, etc responsibly and small successes built on themselves to better general health.
I noticed the same thing around 25, like all of a sudden I was capable of making better decisions on things that make my life better. It coincided with the average age of maturity for the pre-frontal cortex. Felt like a switch was flipped.
I felt the same effect about age 28. It was like I woke up out of a fog. So many things made sense. I also started getting a lot better sleep and exercise by then too.