The number of predictions of future value of bitcoin, is probably only surpassed by the actual price of bitcoin. At least, so it seamed in December. There are several reasonable ways to give a value worth considering. The major one being technical chart analysis. Chart analysis have been financial traders favorite tool for ages, and following some chart-analysis Youtube-channels myself, I believe it is a great tool for predicting prices. But what chart's measures isn't a theoretical or true value, but rather the markets believe in a project and combined with the market's response to the chart itself. Basically the sum of all traders emotional response to a project and it's price change.
A more theoretical way to approach the value of a currency is based in the goal of a the currency, to make financial connections between users. If you only use US Dollars and I only use NO Kroner, we can't trade. But if we both use bitcoin we can trade, and we got a financial connection. The more users a currency got, the more likely two user will find that currency in common, and can use it to trade. That give a network:
The theory of this network is called Metcalfe's law, and number of connections can be calculated like this: Connections = n(n − 1)/2
Getting back to the price prediction. A group of Zurich-based researchers did a calculation of bitcoin based on Metcalfe's law. You can find their paper here:
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3141050
But their conclusion is easier fond in this article from CCN:
https://www.ccn.com/swiss-researchers-forecast-a-slash-in-value-for-bitcoin/
They found that a market cap of USD 77 billion by the end of 2018, that equals a price of USD 4500 for a bitcoin, is likely. Ok, so this value is more popular among crypto skeptics and hostile bankers, than it is in the community. Hostiles and skeptics may give too low estimate to discourage new buyers, while the community may be too optimistic to justify their investment. The best approach may be to make conservative assessments, based on several streams of information, like chart-analysis, news and the network-theories.
To critique the paper, the calculations wasn't completely based on Metcalfe's law, but correlated to bitcoins past crashes, and with some assessments. For instance number of connections was set to Nʌ 2/3 other users. The result of this will give for example: 1 million users is then connected to ‘only’ 10 000 other users, and not 999 999 theoretically possible. Even if it is more realistic, it is still an assessment. I do not personally believe we will see a bitcoin price of USD 4500 this year. A more likely price is above USD 30 000. I won't set a high, for like 2017 showed us, sky is the limit. But this is based only on my opinion.
What to take from this: The ultimate goal of a currency is that the person you want to trade with, accept the same currency as you. Even if the value of bitcoin and other cryptocurrencies increase a lot, they all got a long road to go to reach the ultimate goal of a currency. And what the crypto-community needed the most, isn't more money invested in the market, even if it is nice to see prices soar, but rather more adaption and more users. Then the value won't just be based on a speculation of future value, but based on true correlation to it's usefulness.