I don't understand the meaning of "how many+ noun" here. " how many people " in " It is surprising how many people suffer!" seems to me different from" how many people" in " how many people have arrived ?- Twenty."
. Ah, I see what you mean. I read it the other way-- the sentence is very ambiguous. By the way, now that I look more closely, I cannot make sense out of your 3rd sentence with either interpretation. Perhaps you mean this?--
It is surprising how many people who are using a computer in their own home feel that they are safe from any harm behind the walls.
= The large number of people who suffer ... is surprising. = A surprisingly large number of people suffer ... = So many people suffer ... that it is surprising. ____ The same applies to how much. It is surprising how much money is required to meet expenses these days.