Not everything sells eventually, certainly not for every price. If you seriously wanna make money off the marketboard, you gotta cater to demand. You have some things that aren't super expensive but regularly needed, and other things that are hot on arrival, but drop in price over time. You gotta do research to figure out the former options.

Nothing wrong with taking a break to avoid burnout. If your FC is going to kick you for taking a break from the game, you can probably find a better FC.