Actually, the blame must be shared by both Hamas terrorists and the Likud government of Israel; if Hamas's opposition to the state of Israel must be taken seriously, so too must the opposition to the existence of a Palestinian state, as evidenced in the political platform of the party which controls the government of Israel:
"The platform rejects outright the idea of a Palestinian State a full six years after the Oslo Accords which set out a road map for its establishment. While there is no explicit call for the physical destruction of a Palestinian State, Likud's Platform in 1999 and Israeli policies preceding and following it have ensured that there cannot be a State of Palestine; even hopes for it have been destroyed. Benjamin Netanyahu, remember, is the head of the Likud Party."
This isn't a controversial claim. Israel newspapers covering domestic politics routinely acknowledge this.
Likud and Hamas collude in a game against the residents of Gaza and by extension the West Bank.
Hamas holds no elections and controls the local media by force and intimidation. It cannot survive the creation of a viable, independent democratic state. But by provoking Israel (e.g. with rocket attacks that don't threaten it existentially and are militarily ineffective, but create terror and opposition among Israelis), it can pose as the only dynamically active advocate for Palestinian aims, attracting both followers and financial support from Arab governments. The Israeli disproportionate military reaction, killing mainly civilians not Hamas militants, isolates Israel internationally and makes the civilian population of Gaza ever more resentful and indisposed to trust to political solutions.
Israel under Likud is only too happy to reciprocate. The party's control of government rests mostly on security concerns. The party opposes the creation of a Palestinian state on principle. It too cannot survive a peaceful resolution, so it needs enemies. Hamas is a fine enemy insofar as it is militarily weak but dramatically and indiscriminately violent.
Israel has copies of Hamas membership lists. Gaza is a small place and it is surrounded. If Likud truly wished to put an end to Hamas, it would send troops in to dig Hamas militants out of their urban strongholds and kill or capture thrm. This would require building to building infantry combat. Hamas militants could be effectively targeted but at the cost of many Israeli casualties. Since in Israel the army is well integrated into society and therefore into domestic politics, this would result in disastrous political blowback for Likud.
So instead, it puts heavy artillery on the border with Gaza, and when Hamas militants fire rockets, it responds with shelling. During the invasion of Lebanon, Israel had a record high number of breakdowns among its soldiers, who had to witness civilian casualties at close range, unlike the conventional tank wars it had previously fought. It learned its lesson. Indirect fire from artillery does not allow you to see the child with its intestines eviscerated by shrapnel, or the old lady with her leg blown off, or the faces full of sick fear. It is more like a big video game. You smoke cigarettes with your buddies and talk about giving the bad guys their comeuppance.
Militarily, however, it is ineffective. Hamas militants drive a pick-up truck with a mobile rocket launcher, fire, then drive to a new area before the Israelis can respond, or they retreat back into a parking garage or an alley between buildings. Few militants are killed by indirect fire, but lots of civilians are as apartment blocks and homes are hit by concentrated (sheaved) artillery fire.
The Israeli government knows this. It is elementary military theory.
Eventually, Hamas runs low on rockets, the local population can't stand any more, international pressure mounts, and a cease-fire results with both sides claiming victory. Hamas then rebuilds its stockpiles, and eventually the cycle starts anew. Meanwhile, Israel continues expanding its settlements in disputed territories until they are too large and built up to seriously insist on abandoning or demolishing.
It's a very cynical game.