100GB is practically nothing nowadays.
There are people (myself included, not to brag) running home servers with literally hundreds of terabytes of data. At that ~0.3 GB/day number, I alone could host 3,500 years worth of data. Get some of those r/DataHoarders and r/HomeLab guys on here and Lemmy would never run out of space.
Nah mate, they’ll just download the official Reddit app. You severely overestimate how much the average Redditor actually cares about all this.