As far as I know many settlers work in Jerusalem and commute via the very efficient transport links that the government has built in the West Bank. The Israeli government also subsidises many of the settlements to encourage people to move there. Given high rents in Israel, the quality of life in a settlement can be much higher... large flat, pool etc. Not all settlers are religious nutters, some are poor people tempted by the attractive offers the Israeli government makes them should they move to a settlement. I once visited a settlement near Hebron and was suprised to find that they have a bank Discont (large Israeli bank) branch, and all the amenities available in any town in Israel. It is my impression that Israel has absolutely no intention to ever return this land, instead the government and Israeli businesses are making a concerted effort to expand existing settlements and infrastructure.
4.2-scale earthquake felt in Dead Sea, Jerusalem area (Haaretz)
from the article: UN chief 'deeply troubled' by new West Bank outposts