Nearly every meaningful decision in an enterprise AI programme follows from one architectural choice, which is whether the data travels to the intelligence or the intelligence is deployed next to the data. The first arrangement is faster to demonstrate and is how most pilots are built, since calling a hosted endpoint requires very little setup. The second is what survives a security review, because when inference happens inside the account you already control, a whole category of questions about boundaries, retention, and jurisdiction stops applying rather than needing to be answered.
This is not an argument against commercial models, and we use them constantly where the deployment sits inside your perimeter, whether that is Claude through a cloud provider under your own account, an open model on infrastructure you own, or a combination chosen per workload. The distinction that matters is not which model you use but where it runs and who holds the keys, and framing it that way tends to make the conversation with your security function considerably shorter.
We have built this way for regulated work before. In one engagement for an enterprise with a high-throughput workload, the requirement was that sensitive data could not reach a commercial API at all, so we trained a small language model on their proprietary data and deployed it on GPU infrastructure in their own account, then added predictive autoscaling that forecasts load and provisions ahead of demand. All inference stayed inside their infrastructure, monthly compute cost fell by roughly forty percent against the previous arrangement, and their team runs the system today.