If you're in the AI space you need roughly the same infrastructure as any other SaaS PLUS your LLM costs. Take a look at AWS Bedrock costs [1] and you'll soon realize your costs can escalate rapidly unlike traditional SaaS infra which is easier (er, less difficult) to predict costs.
The dirty secret of an awful lot of these LLM SAAS companies is that AWS are giving them tens of thousands of dollars to bootstrap, which they are paid back for with 8 figure investments from VCs. Anyone who is putting their own money on the line for anything other than the very first $100 or so for a PoC is being conned.
[1] https://aws.amazon.com/bedrock/pricing/