As with climbing Mount Everest "because it's there", this isn't an explanation, it's a refusal to give an explanation.

"Because I can", "because it's there" - that is merely stating a necessary condition. If a mountain isn't there, you can't climb it.

So we are just left to add in the missing explanation for ourselves. Normally it's as simple as "because I wanted to". Of course then you can start dredging for reasons why this particular person would want to do anything so stupid. But why bother?