Here's how to eat a grapefruit just as you would an orange. A food hack, if you'll indulge the term, that saves a lot of slicing and sugaring.
Step 1: Peel the Fruit
Step 2: Remove Pith From the Top Half
Grab on to the pitch near the very top of the fruit, as indicated by the image note below. If you're careful, you can actually peel off the pith, as seen in the second image. Generally, one can only get most of the top half of the pith with this method.
The third image shows the results.
Step 3: Split and Peel Some More
Split the grapefruit in half. Grab the remnants of the stem, noted below, and use that as a starting point to peel off more pith. You can see how it works in the second image.
Step 4: Enjoy!
Take off a slice as you would an orange and enjoy.