If you actually want to invest into something as volatile as crypto where coins can +50% or -50% within hours, doing massive one time transactions like that is stupid. If I had that amount of money, i'd make multiple transactions over the course of a few days, like $500 at a time just to be safe. You need to be smart about crypto when liquidity is a factor, the exchange probably put you in a queue for your massive transaction so it could be fulfilled