Your IP will be added to the list of public relays, which some organizations will blacklist all of. Your IP may also become more of a target in general if you decide to host more than a relay publicly. Your ISP may also not like it, some ISPs disallow hosting on residential plans and may decide to enforce it when there’s significant traffic.
Use different programs, essentially. It’s up to them to interpret the data reported by SMART and represent it. They’re probably reading a value which would actually represent LBAs written, but interpreting it as GB instead.