Thanks for the query,
It is true that sebaceous glands are hyper active in males.
However the size you mentioned is appearing to be a sebaceous cyst
Its better to get it removed.
No it has no relation with masturbation
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.