How much internet is too much? Would you say using >100gb per month is intemperate?

well my household uses 900+ gb a month

Give your forearm a rest and get some sunlight. That is way too much data to be used for anything other then a commercial application.

Get unlimited

depends on the content. I've replaced TV with youtube.

We use an average of 500GB. 100 is next to nothing!

In terms of too much, it's probably better to determine that by time and activity. If you're playing like 30 hours of video games a week, you're probably ignoring other, far more important, aspects of your life.