there is nothing unrealistic about it. as the second comment of this topic mentioned and I also agree, the adoption of bitcoin is like an S curve. these curves have the tendency to be slow at first then the rate picks up and becomes nearly vertical and then it slows down as it reaches the final stage.

with bitcoin we are still in the bottom of the curve and in early stages. what we see as a big rise is simply a small rise in the future. bitcoin is a global currency which is also decentralized. that is not a small thing and exactly that is leading to this growing adoption. soon this rate will pick up and enter the vertical stage of S curve in a couple of years and eventually reach the mass adoption. but in the meantime prices like $50K in 5 years are nothing.