This is a very simple fact, for anyone who is asking how much bitcoin will be worth in next 2, 5 or 10 years just look at history and some answers can be found there. It is not a problem in fact the price of bitcoin grew on average xxx% per year in $ value, but in fact that some people say that at some point such growth will stop. But they ignore the fact that bitcoin is have limited supply, and that it is not comparable with fiat, stocks or gold.

Only 4-5 years ago price of bitcoin was only around $200, and today is x40 - for me quite enough proof that the bitcoin is long-term sustainable and worth the investment.