Evolutionary imperative would be a very simple explanation. The Sentinelese [1] are probably the best example here. They are a group of people that "we" have tried to make contact with numerous times, including with the offering of gifts. The Sentinelese have responded by, for the most part, trying to kill the visitors and occasionally succeeding. But the most interesting thing about this people is how incredibly primitive they are in other ways. They literally have not yet learned how to make fire. Instead when a lightning bolt catches something on fire, they have been observed guarding and trying to keep the fire going for as long as possible. And they have no knowledge of agriculture either.

The point of this is that if at some point people were sufficiently awed or contented by discovered technology your society would start to reach a point where it would simply freeze in time. Instead this instinct we have to assimilate, absorb, bore, and repeat - to no end, is something that seems likely a factor in our (as of yet) never ending drive to develop, expand, and grow.

[1] - https://en.wikipedia.org/wiki/Sentinelese