Someone else already said it, but they only talk with their families once a week. Back when I served it was twice a year, but I think they changed it, because so many missionaries were struggling with derision and anxiety(and found stupid things to cope). Now they are able to talk once a week to help with that. As far as social media goes, I believe it's mostly only Facebook. They can only use it for missionaries purposes. Many post videos or images about Christ and other gospel topics, or share testimony, etc. They can also use it to contact people they're teaching or friends of people they talk to or are teaching. It's only meant to be a teaching tool. Not a glamor thing. You ought to do more research. There's a reason social media stars and celebrities usually get sent to other countries. They're less likely to be recognized as a public figure. All that being said it's still a huge sacrifice even with the advancement of technology and social media. You try being away from home as a fresh young adult relying mostly on members of the church for dinner, when your family used to cook for you every night. Try living by yourself with a complete stranger that you have to spend 24 hours a day with(someone you could become great friends or mortal enemies with). Try having abusive companions, whether it be physical or emotional. Try being rejected everyday by strangers when you have something to share that you know(or at least strongly believe) will make someone else's life better. You try watching your new friends that you're teaching decide they don't want it anymore and stop contacting you. There can be significant amounts of emotional trauma, so you're ignorant if you think there's no sacrifice.