Well, 2.1 and 2.3 is nonsense. TFK is not the cause of it.

And for 2.2, there have been research that both agrees and disagree of a correlation between TFK and cancer, but otherwise, I do not remember anything preverse coming out of doing it too much.

IMHO, it is psychological. As I subscribe more to behavioristic point of psychological view, I'd say you have associated TFK with pleasure (well, tis true..) and thus you continue to derive joy from it. So, start doing other things when you feel like TFK, take your mind off it, that really helps.

Don't fret about the 'dirty' thing. I do not see anything wrong with masturbation, it just just anyone way to experience sexual orgasm. You ever heard of the joke that when you feel horny, go take a cold bath? That do work, as you are merely associating a thought with a unsatisfying action. Your brain will learn soon that everytime it have a sexual thought, it will end up being in cold water.

So, subsitution works, maybe go take a walk or do some pushups or whatever when you do feel bored and wants to TFK, it will allow your mind to refocus on something else.

As I've said, there is no concrete research that mentions TFK causes anything, even the correlation between that and testicular cancer is poor, thus I do not see any problems.

Yes, it carries the negative effect of having to buy more underwear due to wear and tear effects in the long term.

No, no studies have been able to prove otherwise .. So, I guess do go and enjoy those 'experiences', masturbation is frowned upon due to the social view towards sexuality rather than preverse effect on health.