This is a logical argument for why humanity is likely to be obliterated by a space laser, or, unlikely to come across advanced life at all.

Assumptions

1. X light years away from Earth, there is a super advanced alien civilization we call the alphas.

   a. Being super advanced, they have vastly surpassed our own scientific knowledge. By extension, there is no observable knowledge, say biological information, scientific applications like satellites, automobiles, rocketry or otherwise, that the alphas do not already understand to absolute and overwhelming completion and complexity already.

   b. They are not suicidal, nor wish to diminish in civilisational size and complexity. That is, they would choose to remain alive for as long as possible.

   c. It is within their engineering capacity to construct a device capable of sterilizing a planet X light years away, in X years (e.g. electron beam, manipulation of a pulsar's direction, high density photon beam, targeted Dyson swarm, instigation of a gamma ray burst, generation of high-amplitude gravitational wave via black-hole collision, etc).

2. If one were to observe the planet Earth and its solar system as it were, X years ago, one could glean that a lifeform could evolve/form; with a probability far higher than that of the vast majority of planetary bodies.

3. There is a greater than 0% chance for a primitive civilisation to advance into a successfully genocidal civilisation if not contained.

The Argument

1. From assumptions 1 and 2 we know that the alphas at this moment can observe planet Earth as a planet that does or may eventually house life.

2. From argument 1 and assumption 3, we know that a calculation by the alphas would lead them to believe that by not containing planet Earth, a genocidal species may eventuate, that could successfully become an existential threat to them.

3. From assumptions 1A, it can be understood that the alphas can gain no information, knowledge, insight, physical understanding, scientific applications, technological innovations or otherwise from continued observance of planet Earth. There is no utility in preserving planet Earth, or any life that may appear on it.

4. From argument 2 and 3, the preservation of Earth as a habitable planet is exclusively a threat, and not in any way a benefit to the alphas.

5. From argument 4 and assumption 1B, the alphas wish for the continued status of Earth as an existential threat to them to be subsided.

6. From assumption 4, that is that the alphas have the capacity to ensure Earth is destroyed in X years, in conjunction with argument 5, that they have the intention to do so, we may argue that the alphas would choose to deploy their capabilities in removing Earth's status of habitability.

Conclusion

Humanity has approximately X years before we are annihilated, or to flee planet Earth forever.

Corollary

Humanities potential for continued existence depends on the variable X, that is, how far away the nearest super advanced civilization is.

If X is sufficiently far, then we may continue to live for quite some time. However, this also means that the nearest super advanced civilisation is prohibitively far away for us to become aware of them in any capacity.

Alternatively, there may be less than super advanced civilisations near to us. If such a civilisation, the betas are X light years away, and Y years away from becoming super advanced, then the argument follows that we have X + Y years to prevent our annihilation. If we are Z years away from becoming super advanced, then our survival depends on us fleeing Earth in X+Y years, or eliminating the betas in X+Z years. If Z > Y, then we must flee.