MicroStrategy (MSTR) stock climbs 6.9% in premarket trading as bitcoin pushes back up above $51K and MSTR CEO Michael Saylor appears on Coindesk Live.It makes sense to invest in a publicly traded company that invests in an "appreciating asset," Saylor said. "It's impossible or impractical for many pools of capital" to invest directly in bitcoin.On Monday, MSTR bought another 328 bitcoins for $15M.