Happily for your bank account: the 10-step routine is a menu, not a mandate — and Korean skincare enthusiasts say so themselves. The load-bearing steps are the same four everywhere in the world: cleanse, treat (your active, if you use one), moisturize, and sunscreen in the morning. That order — cleanse, treatment, moisturizer, SPF — is the dermatology-endorsed skeleton (https://www.aad.org/public/everyday-care/skin-care-basics/care/apply-skin-care-certain-order); everything else in the cart is elaboration.
What the elaborations actually are: toners, essences, and ampoules are mostly graduated vehicles for humectants — thin water-based layers that add hydration and feel lovely, with the honest caveat that layering five hydrating steps has no trial evidence over one good one. Sheet masks are occlusion plus humectants on a timer: a pleasant 20 minutes, not a treatment category. The double cleanse (oil then water-based) earns its place on nights you wore sunscreen or makeup — which should be most nights — and is skippable in the morning. Eye cream is moisturizer in a smaller jar unless it carries an active you're not already using.
A sane build: oil cleanser, gentle water cleanser, one hydrating layer you enjoy (pick your favorite of toner/essence/serum), moisturizer, sunscreen. Add one active for a specific goal, introduced alone (https://www.aad.org/public/everyday-care/skin-care-secrets/anti-aging/maximize-anti-aging-products). Then — and this is the actual K-beauty spirit — add more layers only if you enjoy the ritual. Enjoyment is a legitimate reason. Obligation isn't.