Citadel's Ken Griffin said investors are starting to view gold as a safer asset than the dollar, a development that's "really concerning" to him.Griffin stated the US is seeing fiscal and monetary stimulus akin to what normally happens during a recession, which is stoking markets, and described the US economy as being "on a bit of a sugar high".Griffin said the $100,000 cost to keep employees on an H-1B visa won't be a major hit for his company, and instead worries about talented students choosing not to come to America.