The AI cost paradox: why are some companies spending more?

The more I look at AI deployments, the less I think AI is replacing employees. It seems to be replacing junior repetitive tasks. Customer support: AI can answer 1,000 tickets simultaneously. Coding: AI writes boilerplate, tests, and documentation in minutes. Research: AI can read 100 papers faster than a human can read 5. But here's the weird part: Several companies are also reporting higher AI bills than expected. Because the actual stack becomes: AI → monitoring → human review → integrations → infrastructure. A human employee costs money because they think. An AI system costs money because it scales. For example, if an employee makes one mistake, one customer is affected. If an AI agent makes one mistake, suddenly 10,000 customers receive the wrong answer. So now companies hire AI engineers, evaluators, and reviewers. This makes me wonder: Maybe AI isn't behaving like an employee. Maybe it's behaving more like cloud infrastructure or ERP software, expensive at first, eventually indispensable. Curious what people deploying AI are actually seeing. What tasks have genuinely disappeared? And what still stubbornly requires humans?