Yes, I totally agree with your statement "Future of Bitcoin Economics depends on mass adoption of Bitcoin. No body can predict accurately the true future of Bitcoin."
We are just betting on its future, we are investing because we believe the price will rise like we see now.
As more people will adopt the price will move up since the supply is limited in number, I like this investment as well as it's not controlled by
anyone and we are given the chance to trade due to its volatility.
The reason for difficulty in predicting the future price of bitcoin is its network-product nature. A network product increases in the logarithmic/exponential proportion. From graphical point of view if you are aware of the parabola graph then you could understand that working with bitcoin prediction is like predicting parabola. The parabola graphs are not easy to work with. Another example of network product is twitter, youtube, whatsapp, facebook, instagram etc etc. The users of these products increased rapidly after they reach the critical mass. Any video becoming viral is like network product result.
Coming back to the Bitcoin, being network product as more and more people start using it market capital will increase accordingly. There are some hedge funds which have made fortune with the investment in the bitcoin. One such example is Bill Miller whose hedge fund has 30% of investment in bitcoin alone. If others also follow this trend then how and when price will increase is beyond anybodies guess.