Would that not also imply that improvements in ease of access to space, increase of energy production and -price reduction all level off before it becomes easy and affordable enough that mere curiosity would suffice to make it possible, for ALL civilizations?

Due to science fiction people tend to forget how miserable life in space is.

Nobody would chose to sacrifice themselves and their descendants (because that's what such an expedition is about), for mere curiosity. And nobody would fund an expedition that will not reach destination before multiple hundreds of years, even if the said expedition doesn't consume the entire industrial output of a major nation.

Space is BIG.