If you don't want to take per-capita emissions into account, and want to look at absolute numbers, then the US has an even smaller carbon budget to work with - and its way exceeding it.
But okay, let's look at per-capita development times quality of life, instead. (China is ~15% behind the US on the latter - does that mean that its per-capita budget should be dropped by a comparative 15%? It's still doing well by that metric.)
You must realize that development is only possible because of access to energy, services, and material goods. Cut the energy, transportation, and services available to the average American by a factor of 3, as a proxy for bringing it's emissions profile down to China's, and tell me - what will happen to its quality of life?
(My prediction is - a sharp decline, followed by a bloody revolution.)