As mentioned elsewhere:
Go on any ship in the night and look for lighthouses that are +50 miles away. Take proper binoculars or a camera with long lenses and start taking pics while coming closer.
That's it. You can do it in the night or a day. The closer you get to the lighthouse, the more of the building you'll see. It's so simple.
Yes, atmospheric distortion limits how far we can see, and it changes all the time. There are videos which show this change day by day from a fixed position because the horizon is apparent, not geometric.
Holding the belief that water is curving over great distances but it is never observable is a belief based on no evidence, against observations which contradict the belief. We fill in the gaps with our imaginations. I never wanted to be this way, but I've gotten over the ridicule that comes with it.
Look, if every single skipper sung the same song I would be less skeptical. But they don't. Same with pilots. A lot of things don't add up.
So seeing something clearly with binoculars isn't truth anymore while random videos online are? 😆
