This issue goes way back......
All my machines run 24/7. They are clean and cool, with proper standby/hibernate settings for minimal power use. They get a weekly shutdown during their maintenance session.
If you have quality components and good airflow in the case, letting it run will not "tire it out". Keep it clean, and adjust the power settings properly. A PC in hibernation uses very little power.
If I owned a stock Dell or HP, I wouldn't let it run while not in use. A Cheap PSU/mobo combined with minimal cooling due to a stuffed case is bad news.
Most of the "Leave it On" die hards I know, swear that powering up the computer sends an initial surge to all connected components, and those repeated surges, over time, can cause an early failure to a number of components.
I say, it depends on what you got under the hood.