Question about Zaheer

Zaheer is a Muslim and he has severe cancer and knows he is going to die very, very soon and since Muslims believe in Hell and Heaven and before they die they try their best to become true believers and please God and not commit any sin, but Zaheer on the other hand, does the opposite and starts dancing and going with some dirty slut and starts to "enjoy life", so isnt this strange or totally against the Islamic principle?

I mean before, when he was healthy he says he has never touched women, never drank or gamble, as its completely against his religion, but now he is dying, he starts sinning? I found it very strange. Or was it the fact that hes angry with God, because hes always been a good boy but God has given him cancer, so he's rebelling against God?