Having low usage on your HDD has nothing to do with your games not running, it might be, but not really.
Your brother is a retard, HDD's last a long time if not thrown or anything else harmful done to them, SSDs in the other hand can longer than normal HDD, cleaning is also advisable.
Main components that may cause issues not being able to play newer games are; Ram, vRam (basically overall GPU aka Graphic card, and videoram does matter, a lot), CPU, nothing else.
HDD and SSD are used for storage, nothing else.