Jonas I would definitely classify masturbation as a potentially addictive behaviour, but I've not been convinced by arguments that such addictions always require therapy. People may smoke and over-eat because they are fruitlessly trying to fill gaps in their lives, but many also do these things simply because they feel nice.
I would reckon that if your main motivation behind masturbation is that it feels nice, it is hard to classify it as addiction unless you spend so much time on it that it prevents you from doing other things. Generally, I would say an addiction is an unnecessary something you compulsively do without really enjoying it. But I feel like this off-topic tangent has overstayed its welcome, so if we want to continue discussing compulsive male masturbation, we should probably move towards another topic. Which is also the reason I will make two different posts here, makes it easier for moderators to split the topic if that is what they decide is appropriate.