I've had plenty of cars without power steering.
when the power steering went on my (larger than the older non-power steering car), the steering was still lighter than on the old not power assisted car...
Whether the car is dangerous or shouldn't be driven depends on lots of things. (in general the answers is probably no!)
If a car has hydraulic assist, and it's gone because the belt that powers that has gone, then it's fine, (though the belt normally powers the alternator also -so might want to get that looked at).
If it's hydraulic assist and the pump is broken then again fine, (though need to make sure that the pump doesn't seize and break the belt).
If there is a hole in a pipe, then you can drive the car with very little worry, except for the fact that the pump still runs, and no longer has fluid in it to cool it so will wear prematurely.
Thankfully, a lot of the small fiats are electric power assisted steering.
this mean that there is a small motor inside the steering column, -so no bits will wear out whilst you're driving around and nothing will seize etc. however it does mean that fixing the power steering can mean replacing the whole steering column, which is around a grand for the parts, then plus the cost of fitting. (i.e payday loan isn't even applicable in this situation anyway!)
Long and short of it is that it's not unsafe at all.