There were Cryptos hiding in the undergrowth back in ancient times when the great banks roamed the World. They lived by the light of the Moon and the great ancient creatures, the banks towering up trampling everything underfoot.
I'm not sure if the banks were even aware of the Cryptos in the early days, they certainly didn't see them as a threat. These small scavengers though, were a new form of life, they were small yes but they were also incredibly adaptive and quick, clever little buggers. Anyway, the great banks started to become worried as the Cryptos evolved and proliferated into all aspects of the ecosystem, changing things, seemigly with no rhyme or reason trying to push over some of the great banks and other great creatures of this age. Of course it was kind of humourous to start with, such confidence, the banks did start to worry though, "If these little creatures actually succeed in their endevours and take over our habitat completely then we will be nothing but relics of the past!" some of them would say. "We must move with the times, use their tactics to our advantage and learn from them, we too need to be clever little bastards.". The banks were already too late yet they didn't realise it, their centralised systems could never operate as cryptos did, they could only try to imitate those decentralised systems, they could never them selves be truly decentralised, they were too greedy and their code of conduct too brutish to succeed. As we all know now, the banks died, we still find their bones and scare our children about a time when these ancient giants would roam the Earth but it's all a fairytale, that time has passed and the age of the Cryptos has decentralised everything, a truly global community has manifested from that first rat-like creature so many years ago, eating insects in the dark, the Bitcoin, which gave rise to all other cryptos.