Absolutely agree. I think that once you've established your civilization over a few stars and planets your survival is pretty much guaranteed against astronomic

Absolutely agree. I think that once you've established your civilization over a few stars and planets your survival is pretty much guaranteed against astronomical destruction (if there's anything huge enough to destroy ALL the stars you've colonized, you probably can tell with billions of years in advance), the incentive changes and you now want to basically go on stealth mode to make sure you don't actually attract any nasty neighbour's attention, because that may be the only thing you can NOT see that may be dangerous. And notice that people from different star systems in the same civilization will very likely only have extremely rare direct encounters due to the brutally long distances involved... it's highly likely the civilization will split up into completely separate "star nations", with their own internal issues to keep them busy and at some point may lose interest even in communicating with other star systems... without any incentive at all to expand further as the species survival is guaranteed... curiosity wouldn't be strong enough, probably, because after getting to know several star systems, you may decide they are look more or less the same, and to find anything really interesting might take multi-million year journeys and no one would be able to embark on something like that just for curiosity.