How can you know that you exist (and in what sense)? Knowing you don't exist seems easier. If you are in a hypothetical taking an action that makes your existence impossible (e.g. acting on a threat that proves unnecessary), then you don't exist, and yet your thinking (including thinking about own thinking) should be reasoned about in the same way as if you exist, to make accurate predictions. You don't necessarily know if your past (hypothetical) existence is proven impossible by your (hypothetical) future actions, so asserting own existence at present can be invalid with respect to logical uncertainty.

Relative claims of existence may be more interesting, such as "Assuming I exist, then this particular future scenario I intend to enact also exists, while that other one doesn't". But the conclusion of own conditional existence would be trivial: "Assuming I exist, then I exist".