A closer look
In 1997, Adam Back invented a brilliant anti-spam mechanism called Hashcash that required your computer to solve a tiny math puzzle before sending an email. For a normal user sending five messages a day, the micro-cost of processing power was unnoticeable. But for a spammer trying to blast out a million fake Viagra ads, it would completely fry their server and bankrupt them in electricity bills. While it never fully solved your junk mail problem, this exact "proof-of-work" concept was later copy-pasted by Satoshi Nakamoto to create Bitcoin. Turns out the foundation of a trillion-dollar crypto industry was originally just a desperate attempt to block inbox garbage.
