On Trading Items
Would you lend your car to a coworker? A friend? A cousin?
I personally would not. But what if you would lend your car out? What if, instead of a car, it was something that could not be replaced? Something priceless and irreplaceable.
Here's another question for you. Would you sell everything you own? Would you then take that money and buy armor and weapons? Would you then take mercenary contracts in active war zones with an eye towards looting the dead in the hopes of earning a few weeks salary?
Would you lend your car to someone who does those things?
Fundamentally, your characters are not you.
These people in games that you are pretending to be did not have a formal state funded education. In some games knowing how to read is a class feature. Their world is fundamentally different than yours.
It is a delicate situation, for we are playing a game and would be well advised to stay away from the non-mechanical interface of what one character would or wouldn't do. But perhaps having this perspective can shed light on rules such as why it takes so long to move safely through a dungeon, why there are rules against trading magic items, and maintaining formation during travel.