What I have heard:

1. Bitcoin is mined by solving complex mathematical equations.
2. The equations (blockchain) are designed so as to limit the number of bitcoin that can be mined.
3. Therefore, bitcoin is as, if not more, valuable than other theoretically limited substances, like gold and silver.

I am puzzled by how a hard limit can be set on mining bitcoin. I understand mining bitcoin takes a lot of electrical power because of computational needs. However, what is to prevent us from going further with either cheaper, more abundant electricity, or faster, more efficient computers?