I have recently looked into email servers (to set up my own from home) and have noticed it is way more complex than web hosting. In a few words, there are explicit safeguards mail servers should follow: basically SPF, DKIM and DMARC.
However I found that of the hundreds of millions of domains that produce emails, way less than 10 million implement those safeguards. Of those few, about less than 1/3 really enforce all of them correctly.
I suppose the breaches via email that happen every day, are partly because of this.
Imagine how ignorant and unaware are regular folks about this, if the very admins of mail servers are this negligent.
People just do not care about safety in communication by email, something that is roughly 40 years old. And if they care, they go for a Big tech solution (Microsoft, Gmail/Workspace, Yahoo).
Project that with bitcoin and all the shitcoins that keep flourishing (13 years old).