Democracy is, at best, a means of peacefully transferring power. If you mean, can representative democracy (a republic) or even a direct democracy (versus an economic democracy), serve the interests of everyone, the answer is apparently “no” for the following reasons.
a) Majority rule is a means by which a group with similar moral codes and material interests can set PRIORITIES for the use of scarce resources. It is not possible to use majority rule for groups with competing moral codes and competing material interests to resolve conflicts over GOALS. Democracy is a means of obtaining majority rule.
b) the lower, working and lower middle classes are and will always be, the largest pool of potential voters. Therefore elites with a variety of interests will simply compete for their votes.
c) the protestant west was unique in that the church managed to break familial bonds by the long term prohibition of intermarriage, and by granting women property rights. Combined with germanic individualism, and the common law, this made possible the fairly low level of corruption in the west, that is endemic elsewhere. It also gave rise the the universalist ethic, which is contrary to the natural familial and tribal ethic. This is a very long topic on it’s own, but basically the west is fairly unique. China and India cannot solve the problem of corruption for example from different ends of the spectrum. India remains familial and china authoritarian.
d) We have fairly good data now, that moral codes vary considerably, and that they are slanted toward the reproductive strategies of the two genders. Therefore those things that serve one moral code often violate another. Those things that violate some moral codes (famlilialism) are necessary for democracy to function.
e) it appears that the philosophers were right, and that a population that can vote itself payments from others will create a fragile economy. This is a particular weakness of the western model versus say the Singaporean and Galveston models, whereby individual accountability is maintained.
f) there are dominant cognitive biases on the left and right. the left is victim of the false consensus bias, and the right overestimates threats and risks, and the libertarians overestimate human beings. These cognitive problems are impossible to resolve by majority rule.
I have to rush so hopefully this brief outline will illustrate the problem.
https://www.quora.com/Is-Democracy-a-viable-system-for-everyone