You don't have to live in a mountain valley to see that the earth is concave (sort of). What you need to do is to see that there is flat, concave, convex, and combinations of the three all over the place. Once you do, you will realize that your post is really humor.



EDIT: Zoom in to the microcosm of your flat floor with a zooming microscope. You will see that the floor that you thought was flat is really filled with all kinds of peaks and valleys. Nothing is flat. Flat earth is a complete lie. The only flat that there is, is the ignorance of people who think that there is such a thing as flat.