Christian's Who Believe Masturbation is a Sin, Why?

I'm a Christian who loves God. However, I don't believe masturbation is a sin. I would like to note that I do however, think that the porn industry is bad and in no way support it or think we as a society should.

I'm not trying to stir the pot or spark conflict, I'm genuinely curious about the different reasonings, as I have yet to hear an argument that sways me.

Edit: Going to respond to comments in a bit, on a zoom call right now. I'd like to again clarify I'm looking to have a serious and genuine discussion on the topic, not trying to upset anyone!

Edit: I don't know if this changes things, but I'm a 20 year old female college student. I specify this because I'm aware that I'm part of a different generation that tends to be a bit more progressive in certain areas.