I just took a massive blow to my Cash?

I come back and all the the sudden I lose 800 billion?

Is this because my new player benefits are out?

The same thing happened to me. I had around 1.2 Trillion I cautiously bought some stuff the could of cost 200 billion at most then a few hours later I was in debt 400 billion so

country and world?

You can check the orders log and see what you paid for stuff.

You can also check the cash flow report. It shows where cash comes from and goes to.

Cash does not disappear.
Cash is managed very carefully by the system and all details can be found if you look for them.

Oh, make sure secrecy is off for finances so players can check and see where the $$ went

One common mistake newer players make is they don't take quality into account when ordering something. If you buy e.g. 200B worth interceptors and ask for 330 quality, then in fact you'll pay 660B and not 200B. If you don't ask for specific quality the game usually orders something around 200 and you may pay around 400B in this example. Not saying this is the case, just thought it might help some...

True,
and it all shows in the log of your purchases.