Python 3 using it to make games and learn Python 3 in Khanacademy

Why do I have to learn a new programming language like JavaScript and I already know Python 3 ?

I already created some games in Python 3 and I want to share it to everybody ! And also Python 3 is very easy to learn. Also when I discovered Khanacademy I wanted to 

1. To learn much more complexe Maths and

2. To share my games in Python 3.

I wish you could understand me, because I really want to concentrate on one programming language, Python. Because if I learn a lot of programming language it is not necessary.