I have no idea if he's upside down. We already heard how high his expenses Are though, and he said he has several years saved. Let's say he spends $130k/year. We'll give him $260k rainy day fund. Mortgage is $720k or so. Student loan debt $90k. His investment makes him $200k/year. Could probably sell that for around $2,000,000 or more.
I'd say he is quite safely positive in his net worth.
You really see has "investment' as debtless? They way he has lived he is no doubt deep in debt on the investment. No way his story could leave any reasonable person to not think otherwise.
I got $90,000 school debt, $800,000 mortgage and on an investment with positive cash flow of $200,000 he owes 2 mill.
I don't doubt he left many other debts out too.