I plan to travel to Tibet. It is said that people who go for the first time will have altitude sickness, which is very dangerous. How dangerous is it? Will you die?

This is for sure, because different altitudes lead to factors such as poor air pressure, and almost everyone who goes for the first time will have altitude sickness, which has nothing to do with age and physique. Most people will have headache, dizziness, shortness of breath, chest tightness, insomnia and other symptoms. Severe cases will have "mountain sickness" such as pulmonary edema (which may lead to death), but those with mild symptoms will also have 1-2 days. So, if you really want to go, I suggest you get used to the environment a few days ago, don't do large-scale exercise, avoid running and keep warm. If you have cardiovascular and cerebrovascular diseases, you'd better not go.