The data here is old now, but you might find this article interesting to give you an idea of the scale of the Internet. Maybe consider that Google tries to keep a copy of most of the public internet (compressed) and assume that the whole thing would be several times larger. Never mind that there is a lot that’s not covered by Google (paywalls, non-public forums/Facebook posts, etc.) but then also services like the Internet Archive that try to make multiple time-stamped copies of the Internet, although I think they usually don’t save the images/videos.

To be short, terabytes might sound like a lot to an individual, but the Internet is several orders of magnitude larger.