As someone who runs a self-hosted mail service in AWS this comment ring true in every way.

One thing that saved us beyond SPF and DKIM was DMARC DNS records and tooling for diagnosing deliverability issues. The tooling isn’t cheap however.

But even then, Microsoft will often blacklist huge ranges of Amazon EIPs and if you’re caught within the scope of that range it’s a slow process to fix.

Also, IP warming is a thing. You need to start slow and at the same time have relatively consistent traffic levels.

Is it worth it, not really no - and I don’t think I’d ever do it again.