What do you use Telegram for? I don't understand its purpose

I'm an American iPhone user that communicates with other American iPhone users 90% of the time. I spend 1/2 of the year out of the country but even then I'm mostly communicating with iPhone users over iMessage. I've used GroupMe, Line and WhatsApp in the past when in groups of international people or to communicate with android users however I don't see the average American doing this.

Basically, I'm interested in Telegram but I haven't really found a great use for it yet. What do you use it for and do you have any recommendations for me to try it out?

Also what is up with all the scammers and ads?