I’m not saying Google was/is running a long con with Gmail. However, if they were, it’s pretty smart to train users not to delete, but to archive, so that they’re slowly using up “free” storage space. Then, years later, completely dependent upon a product and out of “free” storage space, you can begin to charge them. And while the charge might be nominal at first, it’s easy to see how a company might eventually increase the price, knowing how many people depend upon a service.
Please. Buy a domain and use it for your email. Even if it just ties back to a “free” service. This will let you eventually leave the “free” ecosystem without upending your life.
But, also, maybe check-out a paid service, like Fastmail, so at least your costs are predictable.