One obvious answer is that the GDP calculation has become inaccurate. It presents the wrong impression of what’s really going because it fails to capture a whole bunch of alternative non monetary inputs.
For one, real adjustments in standard of living aren’t always captured. Neither is the “added value” delivered from free inputs which are not monetised. Everything from time spent surfing on Facebook, to the beneficial effects of the collaborative economy. Other things hard to quantify: the productivity burst from smartphones.