Correct. You can go to AWS, Azure, GCP, IBM, host yourself, others, if you want cloud infrastructure. It's more or less commoditized.
On the other hand, if you want access thousands of customers who are willing to pay for and use your product ... well that's tough. And it's expensive. The real value is getting exposure to people who will pay real money. Value isn't equal to technical difficulty. That's why Google Ads are pricy, and that's why ads in a niche industry magazine targeting a very specific demographic can be even more expensive.