It's a BIG number. Is it realistic? Although Bitcoin (BTC -0.58%) is sitting as of this writing almost 25% below its all-time high of 73,750reachedearlierthisyear,thereareplentyofbullishcryptoinvestorswhoarestillconvincedthatBitcoinwillskyrocketoverthelongrun.AmongthemisMichaelSaylor,founderandexecutivechairmanofMicroStrategy(NASDAQ:MSTR),whorecentlydoubleddownonhispredictionthatasingleBitcoinwouldbeworth13 million by the year 2045. At last report, MicroS ...