That is it. When you become very aware of just how amazingly far away everything else is, fighting over a speak of dust and the only home we have seems absolutely ridiculous.
A great long form video on this is "Shouting at stars : A history of interstellar messages". It really highlights just how empty it all is.
https://www.youtube.com/watch?v=uFI5WpK2sgg
If mankind exists in 1000 years time and hasn’t regressed then we’ll be able to build fusion powered self sustaining asteroids. Those can be used as airships to colonise every system in the Milky Way in a few million years.
600M years is enough time for Earth to try two or three attempts at intelegence, with full blown fossil fuel replenishment cycles. It won’t be humans - whether we leave for the stars tomorrow or blow ourselves to bits we’ll have evolved to something unrecognisable by then, but there’s very few things which could end life on earth in the next 200 million years (mainly very large out of system asteroids/rogue planets)
My understanding is that ISS is not self-sustaining even in principle. It consistently needs to be resupplied with water and breathable air as the station continuously leaks it. These resupplies happen about once every month or two. This article goes into quite a few details about what would be needed for actual self-sustainable human space exploration and it looks like there's quite a few engineering challenges to work out.
