Yes, some people, maybe even a majority of people, live off of instinct, not for a brighter future or a higher purpose or anything else beyond fulfilling momentary appetites.
But I see it this way. If humanity as a whole was nothing more than the above, no different from any other species, we wouldn't be sitting here discussing this heavy subject matter, on highly advanced machines, that we have made able to connect with other highly advanced machines, in permanent structures with heat, water and other aspects of nature that we harnessed to our uses, probably in a rather safe and durable collection of such structures. Even absent of all of these results of higher brain functioning, there probably wouldn't BE a group called WrongPlanet if we were just common animals, because we'd either be left for dead after being unable to survive or fighting to continue struggling to stay alive, rather than caring what happens to "weaker" members of the species.
For every hundred or thousand people who just live to eat, sleep, poop, have sex and make more of themselves before dying, there's a few people who will try and sometimes succeed to make their life mean something in the grand scheme of things. In my opinion, the few are enough to make the whole seem distinct and meaningful, if nothing else already does.