I used to think the reserve system was just XRPL's version of a gas fee. It's not. It's locked collateral, and that distinction changes everything about how you design for users. Here's the current reality: activating a wallet costs 1 XRP. Every trustline you add after that locks another 0.2 XRP. Not spent. Locked. You get it back if you ever remove the trustline. So a wallet with 5 trustlines has 2 XRP frozen in protocol collateral right now. At today's price that's real money sitting idle just to hold tokens. For users this is annoying. For developers it's a design constraint you can't ignore. If your onboarding flow asks someone to add 3 trustlines before they do anything useful, you've already locked ~1.6 XRP before they've touched your product. The reserve exists for a good reason, it prevents ledger spam. But knowing the exact cost per object changes how you sequence UX. Add trustlines only when necessary. Tell users upfront what gets locked. That's the whole lesson.