How can topic about Bitcoin be way to narrow? I don't get it. You can write about the blockchain technology in essence. You can write about its decentralized nature and why is it important for the world -snip-.
I gave you just some pointers, there is really so many things to write about out there. Just use your imagination and research.
I want a specific question as to which I will do my research on, most of your point here is related to Economics while I'm doing a Comp. Sc. related essay.