To be completely fair, Leah had the god's luck on her side.
She rolled an elf, min/maxed her starting traits to give as much bonus points as reasonable, spawned in a cave with nascent unique mini-bosses who could be charmed into simping for her, got silent take downs on all of them without needing to spend any points on her stats/skills, tried treating non-player characters as you know, living beings on a whim, got the offer to make said cat girl mini bosses her minions and then managed to blind pick the correct combination of loosely related skills that allowed her access to the retainer system.
Most other "normals" who start off in the monster realms are locked into a brutal survival of the fittest scenario so they have to go through the intended growth path, which is to say, spend every exp you get to scrape together an advantage to not dying. Stockpiling exp to experiment with moon shots is as much of a dream as any civilisation's hopes to better themselves when under the thumb of a calamity.
It also appears that most normies don't really think about stockpiling exp or going for moon shot divergent builds, because you're in a use-it-or-lose-it situation. If you don't spend the exp you get, when, and that is a when, you die, you lose it just as readily as the exp you've spent on making yourself stronger that could have prevented you from dying in the first place. Like with money, it's expensive being poor.