Many years ago, a well-established political party coined the slogan:
"More freedom, less state!"
Would you assert honestly that you have never been in a situation where you felt restricted by law and did not understand why you were not expected to do this or that? Did you ever love to pay taxes? So we're likely to spontaneously agree to this slogan! But as good as it sounds, it might well be dangerous to our liberty. Why this?
There are only very few things in life that do affect only one single person and these are normally not regulated by laws. When it comes to laws there is always some reason behind it - protecting the legitimate interests and liberty of some other person. I may not expect that my liberty is granted unless I do respect the liberty of others..
Living together in a civilized society is only possible if there are clear rules and everybody does respect them. But if some people think they are strong enough to disregard the rules, those being treated unfair might eventually turn into an angry mob. This principle holds true for small groups as well as for whole nations. Civilization and democracy are all about defining a set of rules that are acceptable to everybody.
From this we can already derive the most important thing the state has to take care of:
The state must ensure that all human beings living on its territory may live in dignity and that the wealthy do not only talk of their responsibility for the weak but also act correspondingly.
If the state (parliament, government, administration, judges) makes a good job, not only the weak will profit, but also the mighty: there will be political stability and stable, well established rules will allow entrepreneurs to plan huge investments without taking high (political) risks. Otherwise they will not only risk losses due to riots or revolutions, they will also refrain from profitable investments just because of the risks.
If you think this is too simple, take a look at how successful managers of the world's largest companies do decide and you will find that political stability is indeed a key factor. It is not the mechanism that makes the difficulty, but rather the process of building democracy, the negocitating the details of such a social contract - depending on the economic situation of a country as well as on its culture. And last, but not least, both wealthy and poor must be convinced that this contract works and develop trust in it. This may take a very long time: Most European countries took some 200-300 years to establish democratic constitutions from the Age of Enlightment, when philosophers discussed the basics of modern democracy.