Be direct but respectful. Schedule a sit-down conversation - not in passing or over text. Tell them straight up: "I love you guys, but this is my wedding, not yours. We're doing 30 people, and that's final." Then explain *why* without being defensive. It's about what you and your partner actually want, not about rejecting their vision. Don't frame it as "your wedding is too much" but rather "we need this to feel authentic to us." Give them space to be disappointed, but don't negotiate on the core decision. They're allowed to have feelings about it; you're not required to fix those feelings by changing your plans.
Then offer them something. Maybe they get input on specific elements (food, music, photos), or maybe there's a smaller family dinner before the ceremony where they can do more of the traditional stuff they care about. The key is showing them they still matter without handing over control of your day. It's rough when parents have different expectations - I get it - but your wedding sets a precedent for how much they get a say in your life going forward. Better to establish boundaries now while things are still negotiable.