Well, Aboulbaki, let me explain the obvious reason in words small enough for you to undertand:
Catholics, Protestants and Jews all build their churches or temples by collections from their congregations. No one builds them for them.
I realize that in your case that would be your umma which seems incapable of doing the same thing.
I am not aware of a single magnificent, or even modest mosque anywhere in the world that was not built by very rich individuals attempting to buy themselves into heaven; these individuals also happen to be Caliphs, princes or heads of government.
See the difference?
Even in Western countries, including the United States of America, where muslims have the same ability to acquire wealth and status, every significant (magnificent might be your word) mosque is financed by Saudi Arabia, a foreign power. Why any rational infidel country would allow that remains a mystery, and might be a topic for another thread.
It sounds, my friend, that you are very irrationally seeking your enemies to also build your mosques for you.
is there anything that you muslims can do for yourselves?