I think that is precisely what makes it important. As long as as individuals in a society have freedom of choice, the only way to approximate some objective measure of importance is by looking what they value in aggregate.
The things I think are important and the things you think are important are probably different. So who's right? From a practical standpoint, what makes a difference is what people think is important. As the other commenter mentioned, in capitalist society people clearly demonstrate what they think is important by spending their money.
If people chose to spend their money getting their nails done, then they do think that it's important. If enough people think it's important then it becomes so, and no-one can really tell them otherwise. This is the case as long as people have freedom to chose how they make money and how they spend it.
Markets form a democracy: Everybody can vote with their wallet what they want and consider as important.
By deciding to have children or not (and if yes: how many?), parents vote about the distribution of the startup positions for the next generation.
EDIT: In other words: Poor people should rather be angry about their parents than about the system.
1. "Parents vote about the distribution of the startup positions for the next generation." What?
2. "Poor people should rather be angry about their parents than about the system." Are you serious? What good is that going to do?
Sorry, but you must be living quite a privileged, or sheltered life if you believe these things.
The movie Idiocracy satirized one aspect of this, but it still doesn't get much discussion in terms of family planning on a societal scale -- whether to encourage or discourage childbearing, whether some groups should be encouraged more than others and the moral questions thereby raised, etc.
So, acting shocked and invoking "privilege" doesn't move the conversation forward, when there is ample underexplored territory in which to do so.
Wrong.
first, that it can be more difficult for people to get an education (and in many cases, a professional job) depending on their background and thus have a much higher barrier to "cure cancer" type work. simply saying that they could is all well and good, but it ignores some harsh realities of life.
second, the fact that people value something does not necessarily make it important. so what if someone values their nails being done? who does it benefit? capital is a distribution of resources in order to maximise output. some of that output is chaff, but i'd argue that less chaff and more useful product is better for a society to prosper.