What if it's a domain I just don't want anybody to use?

Trouble is that we live in an ecosystem, and "hoard the maximum you can defend, not the minimum you comfortably need" is an optimal behaviour emergent from the system.

An ecosystem with an under-exploited niche will eventually produce the behaviour that fills the niche. It's a self-optimizing system. None of this is fundamentally escapable as long as we are living organisms competing for finite resources.