I agree, its very true that anything can have a value because of us people. Like bitcoin, it has its value because of its all the people who has accessed in it. The value depend on the amount of people accessing from it that is we are making bitcoin be promoted to all.
It is also true that the value of bitcoin is unstable and unpredictable its because it depends on the demand and supply and its up from the developers if they want its value to change.
But we dont need to worry about its value because most of the time the value of bit cough is high enough. We just not to keep on monitoring its value