In that flight of fancy s/he is at epsilon eridani, so that won't be a problem (it's not the size you need, it's the baseline) :-) Anyway who cares about earth-like planets in other galaxies, this one will do fine.
The flaw in the argument is that you need one person with billions of dollars to throw at an ambitious project; of course we could also just decide to do those things collectively, and in fact have managed to do some amazing things that way.
You certainly don't need to have that scale of resources accumulated under one individual's ownership to launch massive, heroically selfless projects for the betterment of humanity. Rather, from the perspective of an individual, there are lots of heroic projects you could attack where there's no foreseeable limit to how much more awesomeness you could accomplish given more and more resources.
The flaw in the argument is that you need one person with billions of dollars to throw at an ambitious project; of course we could also just decide to do those things collectively, and in fact have managed to do some amazing things that way.