Do you want hide your whatsapp profile picture from strangers? Or from all whatsapp contacts?
I will explain how to do that, it’s very simple, you just need change some settings
First, select settings from the upper right menu.
In the privacy screen, you can see several options
Select Profile photo
There are 3 options in this window, your profile picture visibility depends on this settings.
If you don’t care about your profile picture visibility and you want see all people who use whatsapp and have your number see your profile picture, select Everyone.
If you select this option, your profile picture will be visible Only to those who have their number saved on your phone contacts, that means Only those whom you have contact can see your profile photo
Select this if you want no one to see your profile photo, except yourself.