The reserves were built up from the sale of property in London in the 1990's and the subsequent high rates of interest accrued. They were not built up from Capitation Fees. Interest rates are extremely low at present, and whilst there is a worldwide recession, this situation is unlikely to change very quickly.
Although the reserves may appear large, we do need some contingency, if, for example, a Convention had to be cancelled at short notice, because of a natural disaster or terrorism (for which we cannot get insurance). Capitation Fees do not entirely cover current costs and with diminishing membership in some countries, the reserves are the only available source to cover any shortfall.