But that's still 30 years ago so Lego has been fancy pieces and custom kits for a couple generations of kids now.
You can get a 790 piece big box of Lego brand plastic building blocks on Amazon for $35. These types of collections tend to end up in yard sells, or passed around extended families because they last longer than a single childhood. The none-fancy Lego branded blocks still exist, and are still a common part of childhood in America. Lego just doesn't have to market them as hard, and the sale volume is naturally lower.
Then when you get bored with the specialty model as-it-is, the pieces go in the bins and you remix them with everything else :)
This [1] from LEGO Movie specifically plays on the 1980's space sets, for example, and I personally had quite a few of these [2] sets in the early 80's.
[1] https://www.lego.com/en-gb/product/benny-s-space-squad-70841
[2] http://www.doubledumbassonyou.com/2016/02/19/lets-enjoy-a-lo...
I think there were jet packs in the 1970s, too. But I never knew anyone who owned one.