Look, I am a linguist, and I believe that modern Greeks exaggerate their ability to understand ancient Greek compared to modern Romance language speakers to Vulgar Latin. And I'm not the only one. " 'Ancient Greek is to Modern Greek as Vulgar Latin is to modern Romance languages'. If you want to be more specific, a better analogy would be: 'Ancient Greek is to Modern Greek as Italian is to the Vulgar Latin spoken in the Apennine Peninsula'." https://italian.stackexchange.com/questions/1265/is-latin-to-italian-what-ancient-greek-is-to-modern-greek

and

"We must not, however, underestimate the distance between Ancient and Modern Greek, as Professor Hatzidakis has lately done.' The modern Cappadocian dialect, for instance, has developed in such an original manner that it differs from common Greek more than French differs from Italian or Italian from Latin. We may put it generally, and say that the energy of dialectic differentiation in Greek is not less than that seen in the Romance languages; for between the dialects of the Peloponnesus, Macedonia, Cypru and Cappadocia, there is a distance not surpassed by that which separates Italian, Spanish, French and Roumanian." https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/e/68806/files/2018/10/Thumb-Value-of-Modern-Greek-for-Ancient-1uq0czt.pdf