Mentioning below in case it helps someone looking into such estimates:

For a website analytics product that I was building, where every page-view/event stores many values such as browser, device, os, page-params, referrer.. and other typical stuff, it was coming at about 200GB/Billion events, after DB-level compression... the database obviously was columnar.

At these levels of storage needs, things start to cost real deal. With expected monthly intake of just around 10 Billion events, that ramps up to 2TB added every month.

Because of this, I had to move to S3-scaled/backed, nvme-cached architecture, but, that made query times fluctuate to some noticeable extent.

So, that ~4GB-only is for teeny-tiny data per metric sample.. probably 3-4 numeric values at max.