This is quite a bold claim. Yeah "in the real world" you often need to take into consideration the constant factors... but to go this far to say that Big O is useless? It's very useful to figure out what would likely work (or not) for your problem, given that you know the data size - I used it for exactly that, many many times.
Big O says how fast complexity grows, but it doesn't say what that complexity exactly is.
Does something like that happens in real world? Yes, but of course not in such drastic ways.
If you need to pull an example from fantasy world to illustrate your point about Big-O notation not being useful "in the real world" you're probably committing the same alleged mistakes as computational theorists...
You don't really know how this works, do you? I can guarantee that thera are more than 1M particles in the universe. And if you iterate 2^1M times, doing nothing, on a current computer... that's basically indistinguishable from an infinite loop.