I think people in first-world countries should be giving much more money to those who most need it.
But these articles (the ones Oxfam churns out about wealth inequality) are very misleading. Wealth is a slippery concept.
One thing is the way that debt affects the measurement. The very poorest people in the world often have a high quality of life (fucking Alex Jones). You personally have more money than the poorest 30% or the world. If we took your money we could double their wealth (Alex Jones certainly deserves it).
But I think the more fundamental problem is the way that future income is valued. Wealth in the form of stocks is counted based on the market value, which comes from the expected payout those stocks will give in the future. But future income from labour isn't included as 'wealth'. This makes the poor seem comparitively poorer than they really are.
A friend of mine switched from being an employee to a self-employed contractor doing the same job. He pays himself minimum wage from his own company and takes the rest as dividends. Did he really become wealthy overnight through a mere administrative change?
A fairer way to judge wealth is to convert everything to income. Imagine we took all of the wealth of the world's billionaires and combined it into one fund, with the interest split evenly between everyone on Earth. Each person would get about $150 per year. That would be a big help for the world's poorest (poorest in terms of consumption). But it's a much more moderate change than you might imagine from Oxfam's headlines.