How can I convince my parents to buy Netflix?

You mean they would not mind and if my parents watch a show, that's the GZSZ or something.

Your parents do not want Netflix. You do not need Netflix. So the thing is already through

Why should they pay for something they do not need?

Many children already have their own TV sets today! That would be an option for you to justify it.

But if your parents have decided not to Netflix, you will have bad cards!

That's how it has been since the beginning of humanity: whoever pays the music determines the melody.

One more reason for you to learn properly so that you get a well-paid job, then Neflix can buy to the point.