Three months ago, this column argued in "What industrial revolutions actually revolutionise — and why economic growth hasn't changed" that despite surging technology investment, structural growth in real GDP and total factor productivity remains elusive. Investment that outpaces any corresponding return on output is, by definition, a bubble. That said, since upstream industries — semiconductors, for instance — are successfully selling finished products to mid- and downstream markets, even if those downstream applications (AI among them) have yet to turn a profit, a narrow focus on booming upstream sectors will naturally yield a no-bubble verdict.
