early ? when do you think crypto has started ?  bitcoin came out first on the year 2009 and after this others also followed . exchanges are also built along the way and that includes centralized and decentralized exchanges but centalized are the ones that became popular or indemand on other words due to its huge volume ( like what you have stated above ) but aside from volumes  , i think its the stability or the service of a centralized exchange is what makes them better compare to dex exchanges  .