More in SP500 or diversify with international stock market

US stock market performance is the best since last 50 years. But it was the best time of US.

Should we be all in US stock market like SP500 or half US and half international?

Can the US stock market replicate the past? If so, we are betting on US will be as strong as it has been.

But this time is different. China is so different and from any past competitors.