Why a Muslim is using things invented by Christians, Jews like mobile phones, a bunch of medicines, Facebook, whatsapp and many more? Is it allowed?

We as a Muslim, we don't celebrate birthdays and things like that which is created by non-Muslims. But on the other hand, we use Mobiles, laptops, eating products, medicines, trains, and many more daily life things which is also created by non Muslims. Can anyone explain me the reason behind it? Why this partial boycott?