Hamas doesn’t have widespread support. They pretended to be a reformed, moderate, responsible party who no longer wanted to be seen as the extremists that they used to be. Because of this, they won a very slim plurality in the 2006 election and then indefinitely postponed the following election.

Hamas does have widespread support. Maybe not majority, but widespread. They were definitely not pretending to be a reformed, moderate party in 2006. Elections have been repeatedly cancelled not just because Hamas are anti-democratic shitheads (though they are) but also because the PA realizes that there is a good chance that the moderate parties (and I use the term loosely) won't win the election.

Otherwise, support is likely from Hamas daring to retaliate against Israel for mistreatment up to murder of innocent Palestinian civilians over the decades.

Like I said, at least some of the support is because they're the only game in town in Gaza, short of embracing genocide. I agree here.