The biggest flaw in this and similar theories is that it requires 100.000000000...% of beings to decide this is the way to go. Not a single being or entity (corporation, or something more exotic) ever decides, over the whole life time of the civilization that, hey, if we send a space ship over there we can have an entire solar system of our own to play with. Including possibly entities constructed for the explicit purpose of doing that by other entities who do not themselves care. One must also consider that not every being is necessarily limited by our life span too; star travel is effectively impossible for us in our state, but if we casually lived 10 million years and could propagate that in space ships star travel would merely be a massive inconvenience. Plus civilizations can in principle live in denser areas.

This is a general problem across most kneejerk answers, like "humans just suck so hard that there's no chance that they'll make it out before they kill themselves". Possibly true. But to be an answer to the Fermi paradox, it must be the case that all civilizations have that problem, including ones based on insects with strong hierarchies and ones based on super-hippies and slower ones and faster ones and all the ones.

It isn't enough to explain 99% of the problem away, especially if it's done with explanations that aren't even necessarily that good in the first place. You need 100.00%, with several significant digits. (I used more in my first paragraph because that was per being, this one is per civilization.)