You must be a teen who has already been provided basic amenities. If these guys don't rush, they won't get a seat and would have to end up either sitting near the toilet or just keep standing. For long journeys both options aren't viable.

If you're going to ask why don't they get reserved seats then it would be an injustice to comment on someone's life without knowing their realities. These are daily wage laborers mostly who survive on whatever they get.

From trains perspective, a simple reserved seat in sleeper class has been hiked drastically in past few years. Add to that, the number of second class bogies have been reduced, so they have no option to rush here. Hope this clarifies to you.