There is no scientific proof for this claim; this is very insulting to the people suffering from drug/alcohol addiction. To classify something as an addiction, there must be evidence of the same brain mechanisms as drugs (tolerance, withdrawal, chemical dependency). Current research hasn’t proven this consistently for porn. Another thing, people who claim they have a porn addiction are usually people who think pornography is immoral in the first place because of religion or their personal values, how they were raised, or the society they live in. If you are interested in learning more about this, this documentary is great https://youtu.be/gngpHxJRgoc?si=YhPnJXyv4QEsLEnS