Very nice post. I have one remark.
No one has been able to produce concrete evidence that black holes exist, only mathematical models and theories.
This statement is actually not correct anymore, for about more than a year. The LIGO/Virgo experiments have observed gravitational waves that actually consist in the first direct observation of a black hole. In contrast, what the EHT does it to focus on supermassive black holes (LIGO/Virgo focus on stellar-mass black holes), data should be released soonish. By studying the shadow of the black hole, one hopes to get more insight on general relativity and alternative theories.
Thanks for the correction. The release of the EHT findings would definitely have a tectonic significance.