As I said in other comment, it can be boiled down to the term value/effort (which cannot go negative).

Not existing is 0/0 i.e. indeterminate. Existing can be >= 1 (worth living) or < 1 (not worth living, regardless of how much value you get out of life).

Some people prefer indeterminate to < 1. Is it that unreasonable?

Furthermore, some people assign value to not doing something, even if it's a priori. Not being in constant pain (whether physical or psychical) definitely has some value. In that case, not being alive approaches infinity!