What do you mean exactly when you say „not possible to understand“? If we’re talking about complex systems in a physical and/or mathematical sense, it is not true and it is usually possible to understand the global dynamics.

One mathematical example is chaos in a dynamic system described by, say, Lorenz equations. It is indeed not possible to understand any single realization of the dynamics (all of them are exact solutions), but one can understand the structure of the system‘s phase space, which contains the so called Lorenz attractor, a hypothetical, infinitely think subspace all realizations converge to but never will. That said, we don’t know and will never understand the local dynamics, but we see the global rule.

Bitcoin price dynamics is much simpler than any chaotic dynamical system because the underlying „law“ is a simple stepwise-linear deflation process. What makes it complex though are external factors (fiat inflation, markets, wars, fraud, etc.) that massively affect the local dynamics, rendering it completely unpredictable. Not the underlying law, however, which we mostly understand.