I'll attempt to find the source where I remembered that figure. The super high number was for yet-to-be-developed technologies that's badly needed... (next generation radar, ground tracking, PCAS collision avoidance standardization, etc).
Instead of atypical upgrades\market demands\expansions & construction to current aviation infrastructure (1.8 trillion estimates).
https://www.businesswire.com/news/home/20250917931983/en/Airport-Construction-Strategic-Industry-Business-Report-2025-Market-to-Grow-by-%241.5-Trillion-by-2030-at-a-CAGR-of-14.2---Rising-Air-Travel-Government-Investments-and-Smart-Sustainable-Technologies---ResearchAndMarkets.com