Obviously a $5 VPS would give you more raw compute than the Cloudflare Workers free tier.
However:
1. It would run in a single location in the world, whereas Workers (even on the free tier) will run in Cloudflare locations all around the world, close to the end user, reducing latency.
2. If you're going to compare against a $5 VPS, the $5 Workers paid tier is probably a better comparison? It can instantly scale to millions of requests per second.
(Disclosure: I'm the tech lead for Cloudflare Workers.)
10 million requests per month for $5 is about 4 requests per second, correct? Which is about 3 orders of magnitude less than nginx serving static html.
As a comparison, that's akin to a person walking 4 km/day vs. flying 4,000 km/day,
It's still not a great comparison as the $5 VPS is already paid for. But to take it as you suggest, I agree it's up to the website owner whether they prefer to have 4km/day workers who can sometimes clone themselves in different parts of the world but only for a limited time until they costmore, or a 4000/day flying suit.
However:
1. It would run in a single location in the world, whereas Workers (even on the free tier) will run in Cloudflare locations all around the world, close to the end user, reducing latency.
2. If you're going to compare against a $5 VPS, the $5 Workers paid tier is probably a better comparison? It can instantly scale to millions of requests per second.
(Disclosure: I'm the tech lead for Cloudflare Workers.)