Compared to revenue, hosting cost is next to nothing for sites like Tumblr that serve text/image content. A similar video site would need to spend a ton of money on bandwidth, streaming CDNs, encoding servers, etc.
If you get 2.5 million hits a month, it is certainly possible to cover the said selling price of $3m in ads alone in a month.
How do you figure? That would be over $1 per hit.
home_project123 at protonmail dot com
It is non-yukky and does not affect your content/users