A (hopefully) logical cycle...

1) Parents have lots of babies
Reasons: a) they know a lot will die so they want at least some to live. b) Lack of personal restraint.
2) Lots of babies use up resources
What happens: lots of babies all compete for same food source, then they each get little food to survive. Occasionally some do live, but they are often emaciated by the time they are older, then
3) Children grow up unhappy.
They have a disappointed and pained outlook on life, one of the only escapes being to indulge in pleasures. They imitate their parents, as almost all mammals on Earth do.
4) Some may get jobs.
These, due to exploitation by more lucky people, are often hard labor. With lack of enough nutrition because of the resource drain by the high unemployed population, starvation is still an issue.
5) Those people that can survive the longest with the least food win - and the reward is to have more babies... And, usually, lots.

Just some thoughts
~A highschooler