How it works — Each period a new technology's quality climbs an S-curve while the incumbent's old product stays flat. A firm's revenue share of a demand segment is proportional to the R&D capability it has built there. The entrant always commits 100% of its (smaller) budget to the new tech — it has nothing to cannibalize. The incumbent would rationally shift its much larger budget too, but cannibalization reluctance shrinks that shift, letting the entrant's fully-committed capability build-up overtake it despite the incumbent's resource advantage.