I have been self-hosting for over 20 years using self-signed certificates, now widely described by current browsers as "unsafe and suspicious." My clients receive my emails without issue, whether they have Microsoft-hosted, Google-hosted, email servers, etc. or their own private self-hosted servers. As do any other service I interact with via email.

Being bounced as spam not an issue for me.

I'm guessing those horror stories are from people who've misconfigured their mailserver. I've been running my own mailserver for over 20 years now, and have never encountered this problem.

I run my own mail servers on linode and vultr as long as they have existed. Prior to that I had dedicated servers. For a while, I relayed my forum emails through my mail server and it was very rare to be flagged as spam and I never received a bounce or back-scatter.

YMMV depending on who had your IP address previously. If you get a bad (previously blacklisted) IP, then you can always spin up a new VM.

Some of the really low-end VPS providers are so relaxed they get their AS number blacklisted in uceprotect.

Started self-hosting around a year ago. Followed online guides with some tweaks to integrate with my home's Active Directory. Other than that, only had outgoing mail bounce once from mimecast, and after a while they started accepting mail (presumably because of change of my server's ips). Configure rspamd properly and spam isn't an issue.