I think people living in the modern world, with all of our technology are no more happy than a caveman sitting by a fire with his family.

However, to survive as a species in the long term, we need to leave this planet. To do that, we need a number of advancements in technology.

So, if we can agree the survival of the species is in our benefit, then we can agree development is considered a good thing, even if it doesn't equate to an increase in happiness for the individual.