Small holes in a T-shirt: why they always appear in the same place

an important

role.
A frequently cited cause is the belt buckle. If the fabric of the  T-shirt lies directly over it and constantly rubs against it while sitting or moving, the material can become damaged over time.

It is interesting to hear about the experiences of people who have used a different type of  belt and consequently had fewer problems with small holes. However, this is anecdotal evidence and not proof that every case is caused by the belt. (Houzz)

Even a  trouser  button can damage the fabric.