Here is the top-level place so everyone gathers because it is the most flourishing spot.
ここ – here
最高レベル – top-level
栄えてる – flourishing
場所 – spot/place
だから – because
みんな – everyone
集まる – gathers
出身地 – birthplace, where you are from.
繁華街 – downtown, business district, bustling area