You can self host email but less (maybe much less) than 50% of what you send will actually be received by the recipient, particularly for recipients at major providers like gmail, etc.
That's definitely not true. You can either put in the work to improve your deliverability, or you can smarthost through a provider that has a good reputation.
How do you get big co’s like Google to answer your support emails when it is in their best interest for them to discourage the use of any other options?
You don't. Google doesn't have humans that non-paying customers can reach.
As I wrote, either you work on improving your reputation (set up all the acronyms, send lots of test messages, tell everyone you know that uses Google for mail to look in their filtered mail and tell Gmail that your mail is not junk, keep sending, et cetera), or you smarthost through a reputable service.
