Why was the wealthy German immigrant wrong to say he made his money himself?
He was wrong because no one makes wealth independently; every ability and opportunity comes from God. Even his hard work and land acquisitions depended on God ordaining them. Scripture asks what anyone has that they did not receive, and the answer is from God, so all is by His sovereign grace.
Les explains that the old German immigrant had become wealthy and was a tremendously hard worker, but that did not mean he generated his wealth on his own. The pastor asked who gave him the ability to make all his money; he said nobody, I did it myself, and Les says he was all wrong. He could not have made a nickel or bought a quarter section without God ordaining it. This illustrates Paul's point that believers are what they are by the sovereign grace of God, and should not be puffed up as if better than others. What hast thou that thou didst not receive? From God.