Answer :

No, they don't kill you but They may affect you later in life. Sometimes they can cause memory loss or mental problems. Many football players get concussions but they normally don't die from it. Mental illnesses caused by concussions may kill you/ cause you to kill yourself but, the actual concussion won't.
They can't kill you but they can make you suffer with dizzy spells a lot, it happened to my friend the other day and now she has a lot of dizzy spells