I wear my hoodie (which is the hood of a sweatshirt or jacket) every day, about 5 hours of the day to keep extra warm. Do you think that doing this can cause eventual hair loss? That is, with time. You know, maybe in 20 years or so, I will start losing some hair since I wore a hoodie every day as a kid. I'm 19 and am a male.

No.
Defiantly an old wives tale.

If a hoodie or hat rubs against your hair in a harsh way, yes, you might (MIGHT!) experience some hair loss, but the hair would grow back once the hat or hoodie is not rubbing on a regular basis. As for it being permanent hair loss -- NO!

My younger son used to wear a baseball cap backwards with the sizing band across his hairline in front. His hairline started to recede, and he panicked. I told him to lose the baseball cap, and the hair grew back. He decided I was the smartest mother in the world.