Projects which earn primarily from ad revenue, how much is hosting cost?

Projects (apps/websites) that have their main revenue stream from advertisements, should require quite heavy traffic to earn from ads as per ad view payout is very less. But huge traffic incurs huge bandwidth and there comes the hosting or server costs? How many of you break even? How do people manage the initial server costs when the traffic is low?

One interview by Photopea founder I remember: He says that his website is static and all computation is done in the users machine. Only a set of javascript files and html css are loaded once the website is opened. He earned in 100,000s per year, when yearly server costs were negligible because he was hosting a static website. Despite huge traffic, the hosting company didn't charge him much. Why is it so? Is this the case with anybody else?

If you have any case study to share, personal or not, you can share it in the comments! Basically I want to learn on what factor costs depend and in what way. I am a noob at this!