and who of them use it ?
None of them use bitcoin. Who among us really use bitcoin? Very few. The market - literally the people on this forum and many others around the world - have decided that bitcoin is not a currency, it's an investment asset. That's the only reason the price rises, because demand goes up but supply remains relatively low (except for the block awards, etc.)
Rich elites who invest in bitcoin would keep it anonymous for profitable reasons until bitcoin is mainstream.
And many of the rich elite who are buying into bitcoin now aren't doing so anonymously, they're doing so through funds like the Grayscale Bitcoin Trust. They're doing so through investment in private wealth management advisors. They aren't buying direct, i promise you. They don't care about the fundamentals of what bitcoin is...they care that it can make them money.
Actually...who your are referring to are the old rich. The new rich elite are people who were buying bitcoin in 2012. And those people will be spending bitcoin, particularly to fund new projects that will push innovation forward on all fronts...and to buy the obligatory Lambo.