Paul writes in 2 Corinthians 1:9, “But this happened that we might not rely on ourselves but on God, who raises the dead.” Not relying on ourselves. Relying on God.
In the verse before this one, Paul describes how he and his companions were experiencing something far beyond their ability to endure. On their own. If you ever studied Acts, you realize how tenacious Paul is, how bold he is, how much he endures, and how he even endures beatings and imprisonments with singing. After all that time, why did God still want them to rely on Him rather than what they had learned already?