Investing in MicroStrategy for Bitcoin exposure? Don't forget to monitor this crucial metric before joining chairman Michael Saylor's Bitcoin-buying spree.MicroStrategy (MSTR -4.67%) still sells enterprise software, focused on data analytics and business intelligence. However, most investors see it as a direct bet on Bitcoin (BTC -0.62%) these days, and for good reason.Under the authority of co-founder and Chairman Michael Saylor, who also served as MicroStrategy's CEO at the time, the company converted mos ...