This world is already broken and that's the reason people suffer tribulation. The time sin entered this world through Adam and Eve, suffering and hatred became part of this world. Because of sin people face different challenges in life, illness, hatred, death etc. That we are suffering doesn't mean God is directly punishing us, but to tell us that we're living in a corrupt world.
Tribulation can strength us sometimes. During hard times, our faith becomes much more stronger with God. If we pass through problems we learn how to endure pains and we put all our hope in God. In difficult times it easily brings us closer to God for us to serve him in truth and faith.
Some people suffer tribulation because they choose the truth over lie, by preaching the gospel. Jesus already told us that his people will face trouble in this world. The bad people will always want to intimidate you that is following the good path.
