> Lazy loading is frequently a "can afford an extra 5 full time engineers" optimization
I find this figure suspect. I work on a site with millions of users whose core service is essentially displaying a stream of images to end users, and our spend on CDN bandwidth is barely into five figures
I picked 5 at random, but I guess it really depends on where you are. Assuming 5 was the real number, that's only $28k/month bandwidth spend given the average SWE salary in the UK (£38,561 going by google), including 33% for tax and non-salary costs. That's about 327 TB worth of undiscounted AWS bandwidth, or roughly a site averaging 993 Mbit/s.
A small video site might start at 3 Gbit/s, a medium sized one closer to 30. These estimates really are quite conservative depending on the context
It can easily be the vast majority of bandwidth spend even on a lightweight site. Add video widgets and bring that closer to 99%. Lazy loading is frequently a "can afford an extra 5 full time engineers" optimization