"Becoming normal"
For what reason would porn be abnormal? Porn isn't screwing anyone's relationship, it's the unhealthy ways people interact with the porn that does it. Over-the-counter drugs aren't inherently bad, but they're potentially lethal if abused.
I see nothing wrong with porn itself. What I see is that there are a lot of inexperienced people (like my husband) who actually thought porn was realistic and that was actually how to please your partner. I've had to teach him how to please a woman because of that. I also think watching porn WITH your partner can be healthy and very fun. Also watching porn on your own and masturbating are not unhealthy even if you are in a relationship. I don't do it but it's just not my thing. If my husband wanted to I'd see no issues.
The only time I'd have problems with someone watching porn is if they start to prefer masturbating over sex with their partner. If your partner is there and willing you should ALWAYS choose your partner, end of story. Other than that, is porn "Normal" as in demonstrative of what real sex is like? Not really. Is it "Normal" as in something people do? Sure.