Top cryptocurrency Bitcoin (BTC) further nosedived to around $21,000 per coin on Tuesday, a level it saw some five years ago. It was hovering around Rs 20,000-Rs 21,000 per BTC as the global crypto market crashed owing to the weak macroeconomic environment and systemic risk from within the crypto space. Bitcoin has fallen for nearly 12 straight weeks, from nearly $49,000 in March to around $21,000.