Was not same thing happen in Roman Empire?

When government can not support its cost structure, the only ways to make the ends meet are:

1) significantly hike tax rate (income tax, property tax, consumption tax, etc.)

2) military expasion to reap additional revenue resources

3) hyper inflation.

4) cut government spending.

We know 4) wont happen. So the solution will likely be the combination of 1) through 3).

Does your investment portfolio immune to 1) through 3)?