Kinda depends on the perspective - if you want to take up road riding as exercise somewhat seriously, it's the price point where the component quality levels off.
Above that price point, component quality goes up in terms of performance, weight, etc, below that price point it requires compromise you notice even when just riding for exercise (lower durability, bad shifts, sluggish ride feel and so on).
In the world of road bikes, I'd propose roughly these categories:
100-400: bad cheapo bikes. Will ride, but no fun and will break and give you headaches soon.
700-1000: Decent bikes, but you have to make some compromises. Fun can be had, will not randomly break because of bad quality components.
1000-1400: Good stuff, not extravagant. Won't have to compromise on much, you can be satisfied with this forever unless you want to be competitive, and even then it'll do fine.
Unbelievable that the peloton costs that much, what benefits do they actually offer over any alternative?