All Hamas has (or had) to do was not make war. Gaza has not been occupied for about 18 years. Israel provides water, electricity, gas, jobs, currency, tax collection and disbursement services and more to the people of Gaza. Hamas has never been interested in providing these services to their own people. They have a massive natural gas reserve off the coast of Gaza (which Israel found, but ceded to the Palestinian Authority) but AFAIK they never tried to negotiate with any 3rd party to use it to generate export sales, local electrical power, or desalination.
Yep. The sole purpose of their existence is to kill Jews and eradicate Israel.
They keep their people in poverty for a reason. Yasir Arafat Did the same thing.