I work for Vantage and I do think that startups are starting to care about cloud costs, but not necessarily for the cost itself.

The thing to understand early these days is COGS and whether the business can scale its service with good margins. That is a significant change of concerns for investors from the past years where growth was the only thing that mattered.

The other thing that I think is a little off in this post is the idea that startups not caring about costs are a big driver of hyperscaler revenue. I suppose that may have been true a few years ago but AWS, Azure, and to some extent GCP are having a lot of success moving legacy on-prem deployments to the cloud. It's not uncommon to encounter 50 year old enterprises with a billion dollars of cloud spend. One example of this is the dedicated SAP instances that AWS has, some of which cost $100K per month.