There's money in misery:
Since Hamas took control of Gaza two years ago, when they defeated Fatah (militarily, and at the ballot box), they have found out how to make money from misery. First, they had to turn Gaza into a police state. Then they took charge of the economy by controlling what goes through smuggling tunnels, and what people pay for it. While Hamas complains about the Israeli blockade, which is in place because Hamas refuses to stop demanding that Israel be destroyed, and bringing weapons (especially long range rockets) into Gaza to make that happen, they would go bankrupt if the blockade were lifted.Jeez, you'd think canny Jews would figure out some way to profit from this rather than executing expensive tunnel-busting air strikes.
These smuggling operations are so lucrative that Hamas deems them legal enterprises, and charges a $2,500 fee for anyone who wants to build and operate a tunnel. In addition, armed Hamas revenue collectors stand at the Gaza entrance for each tunnel, demanding a payment for everything coming out of Egypt, or going there.
Referred by reader minicapt.