Proton!

The fuck if I'm gonna let Google train an AI off my emails.

Some people do. There are options (like Proton) that offer good services that respect their users and their privacy and I personally like to support that

A lot of us pay for privacy focused email because we don’t want Google or MS steal our data

Aye, as @forensic_potato said. And they have really good free options too, that are actually improved upon feature wise (only usage is limited)

Gonna pay once I can actually afford it.

You have to pay to get a real domain