I think that just shows how narrow your group of acquaintances is and how out of touch you are with a large part of the world.

250 million people use Pinterest every month. That's (approximately, though lower than) the same ballpark as Snapchat and Twitter.

I assume you are capable of Googling their monthly user numbers, just like I did. So I assume your post is just virtue signalling and not actually asking in the spirit of trying to understand others, since it is obvious that yes, people do use Pinterest.