What is the wisdom behind Allah's decree of events and His deprivation of valuable possessions that a person toiled to acquire, and what good is there in that?

What the questioner mentioned is a trial and a test for which man was created. This world is a realm of trials to distinguish the wicked from the good, the obedient from the disobedient, and to reveal who prioritizes pleasing God over their own desires, as Allah Almighty said: "He who created death and life to test you [as to] which of you is best in deed." (Quran 67:2). This test encompasses both religious and predetermined decrees, such as good and evil. Allah Almighty said: "And We test you with evil and with good as a trial; and to Us you will be returned." (Quran 21:35). For a believer, this trial serves to expiate sins, elevate ranks, distinguish believers from hypocrites, or as a punishment for some sins.