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.)
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.)