The essential problem is the failure to understand that global wealth is a finite resource. As such, when a greater amount is held by the small number of people at the top, by definition it has to be taken from those elsewhere. Greater poverty is the essential, inevitable and unavoidable consequence of the harbouring of wealth.
Hence, the need to forcibly redistribute said wealth.
I don't think everyone is entitled to an equal share of the pie. Some people truly work harder than others (ignoring the realities of social influences on success), so they earn a better share of the whole.
I just don't think anyone or any group consisting of 1% of the population earns a 90% share of the whole.