Why established powers fall behind

Established powers carry commitments that make the next generation of military investment harder to justify, while rising powers have stronger incentives to pay the entry cost. Britain's Cold War focus on its army on the Rhine and growing internal commitments is one example of priorities reshaping external power. Other empires decline after losing wars, losing the money needed to recover, or losing interest in the systems that sustained their position. Remaining at the top requires maintaining existing capabilities while funding unfamiliar replacements. Repeating the same investment cannot preserve control of trade routes indefinitely.