I won't talk about the s***show we're experiencing right now, going from an overvalued BTC to an undervalued one, but in the 2013-2016 period this is what the chart shows...
I don't see how Bitcoin or crypto in general can ever be undervalued. Most of the demand comes from people speculating about the price to increase, and when they exit the market, the demand exits as well.
In other words, Bitcoin goes down and will be valued to a point where there is enough demand to keep its price above certain levels. People have to accept the cycles we're going through.
People buying in right now hoping for a quick recovery to the $20,000 mark are delusional. Bitcoin currently looks cheap based on its 2017 high, but you can discard that high because of the hype madness we don't have right now....
I value cryptocurrencies in a different way,
The value of all of the world's coins and banknotes are roughly 8 trillions. People use these
papers to buy goods, to save them in banks (and hope they'll be able to withdraw them without capital controls), to move inside a wallet which can be stolen, to send them overseas with high fees and with least a day's wait (if it's not a weekend or a holiday). People give these
papers money allowing those with the printing machines to decide everyone's wealth and buying power.
If such a paper has a market cap of 8,000,000,000,000$, then how much should BTC have? On it's early stages, I'd say 1%, which is 80 billions. We've gone through this as expected but we reached 300 billions in a very short time, that was too soon too fast, but falling down to 60 billions instead of moving up to 2% of USD's market cap is "undervalued" in my eyes.
Then similar things can be said for different coins... for example compare the volume of XRP with the volume of WesternUnion and MoneyGram (I haven't done that though).
Or compare the amount of money that is spent in mobile games' microtransactiosn to the ETH transferred within DAPP games (I haven't done that either!).
I like to keep everything in perspective and compare things which are as similar as possible, that way I believe I can find where the price stands.
I also have made a thread about that:
https://bitcointalksearch.org/topic/m.48265856If you believe that in a 100 years BTC can be as big as USD (which is at most 1/5 of the world's money), then BTC should increase by 80 billions every year on average.