The main idea of this sentence is that Lin Chong jumped out to support Song Jiang as the master of water margin. According to the truth, Lin Chong will not be demoted by Song Jiang even if he is not promoted. But this sentence has a background.
First of all, Lin Chong himself is very good. Among many heroes in Liangshan, his force is also very strong. He always speaks immediately and is good at beating horses. Moreover, Lin Chong once worked as a coach of 800,000 imperial guards, which was very prestigious. Plus, he went up the mountain very early and is also a veteran of Liangshan. Such a Lin Chong is a good candidate for Liangshan leader.
Then, before he died, Classical put a Song Jiang together. He never liked Song Jiang and didn't want him to be the leader, so he said that he could avenge him by his own strength, and Lin Chong, who was valued by Classical, became a strong competitor for the leader position. Sung river will naturally beware of Lin Chong.
Finally, Lin Chong publicly elected Song Jiang as the leader when Classical died. Song Jiang did not avenge Classical according to Classical's statement. Second, Classical has just passed away, so we can't worry too much. In this embarrassing situation, Song Jiang will naturally think that Lin Chong deliberately embarrassed him, so he did evil.
Lin Chong is a talented person in all aspects, but his political acumen is not enough. He originally recommended Song Jiang with good intentions, but because he chose the wrong time and was too hasty, he let himself be rejected by Song Jiang. This is a thankless thing.