Zeuskabob I'm assuming you're referring to the values found in Settings > Storage? If so, I personally think that the label "temporary system files" isn't very clear and can confuse people. A developer told me a while back that the value there is simply storage that doesn't fall under other categories.
This came up a while back and it turned out the people who were experiencing this problem just had other profiles with a lot of used storage. If you also have profiles with varying amounts of used storage, you can switch to those profiles and check again and you'll see the number changes. If you add up all of your profiles' used storage, except for the active one, and subtract that from the temp system files value, you'll find it's pretty reasonable.