Israel has been under attacks by Iran backed proxies which all happen to have been attacked by Israel first.

1982, Israel invades Lebanon. Iran backs Hezbollah, which triggers its first killing of Israelis in 1983.

There would have been reasons to back the creation of Hamas long before 1982 but the revolution in Iran only took place in 1979, so through the decades of Palestinian oppression, massacres and occupation, Iran was aligned, so it started with a support for Lebanese resistance. Then much later the backing of Palestinian resistance, then Yemen via the Houthis.

It is true there has been constant funding, and of an increasing number of proxy groups, but Israel's invasion was the trigger. Backing nations, and paramilitary groups is pretty common: see U.S backing Ukraine regular army, and private mercenaries.