Why does oxygen form O2 while sulfur forms S8?

[Dragosagaragarwal]

We know that catenation property decreases down the group...
Then why oxygen exist as O2 molecule while sulphur exist as S8 molecule

 

[Bystander]

We know that catenation property decreases down the group...
Then why oxygen exist as O2 molecule while sulphur exist as S8 molecule

P₄ vs. N₂?