Too much protein can definitely kill you, or at least make you ill, as discovered by the Europeans who explored the northern parts of America and who had initially tried to live from the meat of hunted animals, until they learned from the natives that they must eat enough fat besides the lean meat, in order to survive (most wild animals have little fat, except the bone marrow, which must be extracted).

However, too much protein is a lot, much more than most people will try to eat in normal conditions, because an important advantage of protein is that it is satiating, i.e. when you eat enough protein it is easy to eat less food and more seldom, without feeling hunger.

For example, I eat 2 meals per day, in the morning and in the evening, of about 800 to 1000 kcal each. If I ate more, I would gain weight rapidly.

When I was eating any kind of industrially-processed food, I could not eat so little, because I became hungry quickly. Now I eat only food that I prepare myself, from raw ingredients. In order to avoid hunger, the content of protein and fat is very important. Typically, each of my 2 meals includes 40 to 60 g of protein and 20 to 30 g of vegetable oil. This ensures that I will not be hungry all day.