Haredim marginalize women, don't educate their children in secular subjects so if they do decided to work, those children are not prepared to work in a modern technological society. Haredim in Israel choose not to work, and take welfare from the state, funded by a relatively smaller segment of the Israeli population that do work and pay taxes. Most do not serve in the IDF. If the Haredim weren't a rapidly growing segment of the population, their lifestyle wouldn't matter. However, because of their growing population and political power, at some point, unless things change, Israel will less effectively be able to defend itself militarily and economically.
from the article: 'New' generation shaking up Israel's ultra-Orthodox political scene