Python 3, 52 bytes

from random import*
while 1:print(end=choice('/\\'))

Try it online!

Saves at least 9 bytes over other python solutions here.

Python 3, 52 51 bytes

from random import*
while 1:print(end=choice('\/'))

Try it online!

Saves at least 9 bytes over other python solutions here.

Edit: saved a byte via ayreguitar's comment