The interesting part is that you absolutely don't need a telescope to see the horizon and the curvature. A simple play that a lot of us did when we were children, I guess: on a beach at sunset, just lie down flat on the sand and look for the sun to disappear under the horizon. Then, in the moment that it disappears, jump up as quickly as you can and you'll see the sun disappear behind the horizon once more. Actually, it works better for adults than children... :-)
With the proliferation of cameras, it is actually equally simple to make proof of this, if you happen to travel somewhere where tall structures can be found (not necessarily as tall as the famous Burj, although that altitude really helps). All it takes is two people with synchronized cameras to make a short video of the sunset, with timestamp visible, from both the ground level and the top of the building. With the Burj, there will be minutes of difference between the sunsets, with a smaller building, proportionally less but still easy to demonstrate (if the timestamp displays seconds, a usual skyscraper will suffice). And this can be done by any couple of FE enthusiasts themselves, so the question of "government falsification" is moot.
Note: I registered specifically because I was intrigued to see that there really were people who claim that what mankind has known for almost 2,500 years is false and part of a conspiracy plot. :-)