The man in today's Gospel was already rich (Lk 12:16). He had several grain bins on his property (Lk 12:18). It had been a year since his last harvest, and still he had no room to store this year's harvest. Therefore, his grain bins contained at least a year's foodstores in reserve. Then he "had a good harvest" (Lk 12:16), so large he was bursting at the seams. God blessed this man in ways foretold by the prophets (see Am 9:13-14; Is 30:23-25).
This man's speech reveals his heart (Lk 6:45). Though rich, he was worried about his future. He could have thanked God for a bountiful harvest; instead, he told himself he was finally financially secure enough to "relax" (Lk 12:19). He could have shared his plenty with the hungry, thus growing rich for God. Instead, he only thought of growing rich for himself (Lk 12:21).
The man rejoiced most of all because he trusted in his reserves rather than in God. When deciding how to handle his harvest, he consulted himself rather than God. Now he would be self-sufficient, independent of a God he never thanks or mentions. His actions and words show he does not trust the very God Who continues to bless him so abundantly, Who cannot be outgiven, and Who continues to provide for him. In His mercy, God reserved a place for this man and all others who insist upon being independent of God "for years to come" (Lk 12:19). It's called hell.
Some of us could also fall into this "trap" of desiring to be secure for the rest of our life (1 Tm 6:9). Repent! Trust in God alone.