The problem isn’t spam, the problem is you becoming the spam.

I did test email selfhosting before and there’s a substantial amount of times my emails were never seen by the recipient, sometimes it did cost me good jobs/deals.

So now I use paid email while I control the domain and everything else, so I have the portability feature if I wanted to switch providers without any efforts, but I know now my emails will be delivered whenever I hit sent.

That being said, I self host everything else in my digital life, and I believe everyone should.