If bandwidth is your highest cost, that's a completely separate problem that likely requires CDN. Neither x86 or ARM is going to reduce that cost.
We serve 200+ TB/month, and no we didn't just forget to use a CDN ◔_◔ Those cost money, too.
For us, cloud is about double - $10k/month more - than dedicated boxes in a data center. I've run the same system in both types of environments for years at a time.
For us, cloud is basically burning money for a little bit of additional safety net and easy access to additional services that don't offer enough advantage over the basics to be worth taking on the extra service dependency. It's also occasional failures behind black boxes that you can't even began to diagnose without a standing support contract that costs hundreds or more a month. Super fun.
High bandwidth and steady compute needs is not generally a good fit for cloud services.
And no Cloudflare's cheap plans are not an option, they'll kick you out.