Honestly I'm mosts impressed that the example gif is only ~480kb despite being high quality and pretty long! How did you do that, author?
GIFs we see on social networks are typically captured from videos of real-life objects, places and people, so the source colour-depth is pretty high (to account for the necessary shades created by varying exposure to light in three dimensions) and thus even a poor-quality GIF is going to be quite big to represent the source media with any discernible accuracy.
Since that terminal sports very few colours, it can be saved with low colour-depth and thence remain very small, despite size and length.