A hundred billion? I don't actually know, but that seems too high. I've worked as an automation engineer in a bunch of factories and know that you can get a fairly complex fairly large factory for 9 figures. I know semiconductors are complicated but so are a lot of things. I'd guess it's closer to a billion depending on scale/size/location.
5 years to start up a factory is fast, but doable.
Maybe it has a bunch of leaked files from the WarThunder forums as well!
Simulating battle scenarios is absolutely hilarious, adults standing around the magic 8 ball