you are looking at it too simply. the government prints money, because it needs to. it prints more because of the way banks work, and in the states, the federal reserve.
to really understand this you would need to take economics courses, but i'll try and help you out.
if everybody printed their own money, everything might as well be free for one thing, or if the government just printed more and more, willy nilly giving everybody a million dollar pay increase every year, inflation would go through the roof like crazy.
however, (i'm not totally sure of how it works in the US, but i think it must be this way) in the US the federal reserve lends money to banks, the federal reserve sets the interest rate. this controls the spending of the people living there, and how people use banks, i.e. either for saving or borrowing. since the federal reserve has control over this, it can control the rate of inflation.
if everybody had money printing devices in their basements none of that part would happen. that's why you can have one and not the other.
i don't know what you mean, businesses using fake money and dot coms with no actual value. a thing has as much value as people are willing to pay. i'm not willing to pay anything for monopoly money. but i am willing to pay for a dot com that is technically worth nothing, because it could be worth something some day and if i pay less for it now, then it will be worth in the future, i made money. if somebody is willing to pay for something it has legitimate value. there is no authority that goes around placing price tags on things.
tangible doesn't really matter. stuff doesn't need to be tangible to be worth something. time is worth something, banks pay extra for security, as in will choose to pay almost certainly too high interest rates, just so they can set it now, so they can be sure what it is.
an idea can be worth millions. but these are so easy to steal. but if you have an idea and the rights to it. then you have something you can sell. you can sell it for as much as people think will make them money in the future if they buy it now. ideas like dot coms.
in terms of value, the only thing that matters is what people are willing to pay for it. that's all the tangible you need.
even just a false rumor can cause stock to rise or fall.