To me, this seems to vastly underrate the scale of the universe. Even if our galaxy had significant amounts of life in it, and civilizations were sending out hundreds of Von Neumann probes, it feels improbably as heck that we'd have seen any in this brief modern stage of human development where we could spot such things.
Second, life just seems not easy. Intelligent life doesn't necessarily have conditions to be sending out masses of timeless void travelling probes on and on. Probably a lot of the advanced ones struggle or lurch along as we do trying to subsist off the local ecospheres.
VN probes work more like the lily pad riddle that humans commonly fail to understand.
>In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake?
The answer of course is the answer 47 to the riddle. With VN probes the answer would be "who the hell knows" at this point. Maybe interstellar space is a whole lot more dangerous than we expect and sending out countless self replicating probes isn't possible. Maybe the intelligent aliens out there are a whole lot smarter than us, and the idea of sending out probes that you effectively lose control of is recognized as a bad idea. Or, maybe there is no one else is out there. Hard to figure out with a sample size of one.
Second, life just seems not easy. Intelligent life doesn't necessarily have conditions to be sending out masses of timeless void travelling probes on and on. Probably a lot of the advanced ones struggle or lurch along as we do trying to subsist off the local ecospheres.