I guess so. He did have an upbringing that was in difficult circumstances.
His family was from Majdal. The town that was forcibly taken over by Israel. There were 9,910 Palestinians in Majdal community of Islam, Jewish, Christian and Druze identities. All were displaced out and their homes demolished. Majdal town was one of the 102 communities displaced by Israel soldiers and built over with new settlements (overall 499 towns and 1196 known mixed communities displaced).
Sinwar grew up in refugee camps impoverished. His clothes were gunny sacks sown together. It is perhaps why he founded Majd, the precursor to Hamas.
Maybe Majd is in reference to his birthplace the displaced town Majdal?
There are millions of Jews, in Israel and other countries whose roots were in places like Baghdad, Cairo, Alexandria, Damascus, Tehran, Tunis, Warsaw, Berlin, Lvov, Kiev Odessa, Salonika, Budapest and thousands of other places who were (at best) displaced virtually penniless or were brutally murdered.
None of them are living in refugee camps waging terrorist campaigns against the people who displaced them. None of them are demanding a right of return to those places. Probably because it's part of the peripatetic history of Jews since the earliest times, they just accepted it and moved on.
Yet countries like Iran, Yemen and Syria seem determined to displace Jews from the country they displaced them to in the first place.
Why did the Arab countries refuse to integrate the Palestinians displaced in 1948? Because it suited them to use them as pawns in their beef against Israel is the answer.
Why did Jordan not set up a separate Palestinian state between 1948 and 1967? Because they saw the West Bank as Jordanian territory is the answer. And when the PLO decided they were a law unto themselves in Jordan, Hussein massacred and expelled them.
The Arab nations had no interest in a two-state solution when they could have implemented this themselves, they only became interested when it was Israel's problem.
You can blame both sides for their intransigence in more recent years and it's been the bad luck of the Palestinians in Gaza that they were under the control of an extremist, anti-Israel terror group that has no regard for their lives and safety, and which made a fatal miscalculation last October. And on the other side they are faced with an extremist right-wing Israeli government who equally has little regard for their lives and safety.
But you can't ignore the history. There are lots of 'what ifs'. The former Israeli foreign minister Abba Evan summed it up: "The Arabs have never missed an opportunity to miss an opportunity".