2 MB per day doesn't sound like a lot. The amount of posts probably has increased exponentially over the years, especially after the Reddit fiasco when we had our latest, and biggest neverending September.
Also, I bet a decent amount of that is not from humans. /newest is full of bot spam.
I suspect it is closer to 100% increase for the average comment. If the average comment is a few senteces and the metadata has id, parent id, author, timestamp and a vote count that can add up pretty fast.
Also, I bet a decent amount of that is not from humans. /newest is full of bot spam.