The young pool players seem to take pride in their aimless behavior, and critics have debated whether they may also take pride in the prophecy they will "die soon." They live in a culture where even the most talented people find that economic and social opportunities are scarce. Dying early could seem like a badge of honor. On the other hand, the last line could be read as evidence of the speaker's disapproval as she tries to pop the boys' inflated sense of pride like a balloon.
The phrase "die soon" expresses the boys' pride in placing such little value on life.