The issue with any cloud/vps provider is they usually have a max monthly bandwidth. Hetzner dedicated (not cloud) usually gives you unlimited (reasonable) bandwidth at 1Gbps
And yeah the point of the cache is less about the burn on the box of the request but more the capped bandwidth at the machine level, whereas content being served from the cdn can scale to a shit ton of users and only comes from your box once within the cache expiry time