Being an older sibling is not without its advantages. Even your slightest milestones are documented, you never have to suffer the indignities of hand-me-downs, and you get to act as a third parent when additional authority figures are needed.
But younger siblings get to break more rules. Parents sometimes get lenient with second and third children; enforcing strict mandates after the first kid gets exhausting.
Older siblings usually notice the injustices, too, and they describe the situations on Reddit. They usually know their parents don't love their siblings more, but it's still tricky to accept younger siblings' seemingly easier way of life.