That's what your nose is for. (I'm quite skilled at advancing or going back by gently tapping the kindle against my face. It helps that I'm very nearsighted so it's kind of already there)
Only way to get buttons that are comfy on both sides would be to flip it screen out. That doesn't seem like a very useful position to hold a reader in though.
If you turn it upside down the left hand buttons will be way too high on the reader