Because you can swirch it off and walk away.
Doesn’t mean it’s not real life.
I can go home from work and not think about it at all, but that doesn’t mean it’s not real.
The Internet is real life, just like any other method of social interaction.
I can go somewhere where nobody knows me and pretend to be someone else, if I treat people badly while I am there, they are still offended/upset etc.
it’s still real even if I was anonymous while I was being a prick.
People are still people, even if they are conversing online.