No reliable way to validate whether a total trip budget is realistic across multiple countries and currencies

Summary

Travelers planning long, multi-country trips cannot confidently determine whether their total budget will actually cover months across regions with wildly different costs and currencies. They are forced to manually estimate, post their itinerary on forums, and rely on strangers' guesswork. Existing budgeting apps only track spending after the fact and do not forecast feasibility, flag risky assumptions, or suggest adjustments for currency swings. This creates persistent anxiety and the very real risk of running out of money mid-trip, making it a high-value, largely unsolved planning problem directly tied to cross-currency budget management.