Self-hosting inference is seductive and frequently a mistake. It promises control and delivers an on-call rotation. We treat BYOC as something you earn with evidence, not something you reach for by default.
What managed providers already capture
Before any BYOC conversation, we want to know what provider-native caching, batch tiers, and alias routing already deliver. In a lot of workloads, Anthropic explicit caching or Gemini implicit caching plus a batch lane captures enough that running your own KV hierarchy would not move the number much.
The three reasons that survive scrutiny
BYOC tends to justify itself for three reasons: a dedicated latency SLO that managed tiers cannot guarantee, sustained hot-model volume concentrated on one or two paths, and isolation or purge requirements that need runtime-confirmed evidence. Long prompts are not on that list.
When one of those is real, explicit KV orchestration with Dynamo, SGLang, FlashInfer, and LMCache becomes worth the operational weight.
Prove it with replay
The bar is a replay run: take the captured workload shape, run the managed baseline against the BYOC candidate, and read the signed report. "Eighteen percent cheaper on the same traffic with equal capture" is a decision. "It feels like it should be faster" is not.