[jerf]

"Why have they not bothered to come get us yet? We have our own nukes. They waited a little too long, or so it would seem."

Oh, any alien genocider that may or may not exist would still be thoroughly unimpressed by our ability to fight back. Anything that could cross the stars in any period of time since civilization started need simply ram Earth to wipe humanity out as we know it. Call it a 10000 kilogram craft travelling at one-thousandth the speed of light from Alpha Centauri, setting sail 4000 years ago or so; if that simply rammed Earth it would be ~150,000 Hiroshima bombs [1]. That's pretty conservative for a genocider's capabilities, really, too. Obviously they're not right here, so anything that can travel here in time to get us is also a weapon that can wipe us out.

(This is to say nothing of the extreme opposite end of the scale and what a mature nanotechnology ought to be able to, even without Drexlerian extremes. I sometimes ponder "Our entire civilization was uploaded in its sleep ~3000BC and the real Solar System has long since been converted to computronium, and the simulated universe is lifeless to keep the processing simple." Pick your date of upload to suit your taste.)

To be clear, while I remain open-minded my current "top-probability" pick for resolution to the Fermi Paradox is "life is far more rare than science currently guesses". But it's still fun to discuss the alternatives and it's not like I could put that even remotely near 100%... it's just my best guess in a field where we have virtually no data, and YMWV.

[1]: https://www.google.com/search?q=10000kg++*+%2830000km%2Fs%29... - 63TJ is the Hiroshima explosion size.