This study is interesting, but misleading, if one takes it as support for "bitcoin is real, and altcoins are shit".
The initial period of bitcoin can show tremendeous value increase, because bitcoin was the very first crypto currency, and initially, nobody thought that the CONCEPT of a crypto currency could even work, so it started out as essentially worth NOTHING. The rise from "nothing" to "something" is in fact infinite, and it is because the curve for bitcoin doesn't actually start at "nothing" that you can even put bitcoin on the chart.
But one can only discover ONCE that crypto currencies can function and get value. That was bitcoin. No crypto currency EVER after will start at "nothing". People now KNOW that it can obtain serious market caps. So no other crypto currency can display a rise from essentially nothing to something, showing several orders of magnitude increase like bitcoin can in its first years of existence.
But EVEN BITCOIN will not have such value increase any more. These crazy rises are over. Only the first one could display that, not because it went HIGH, but because it started SO LOW.
Like the other thread said: "nobody's buying pizza for 10 000 coins any more".
So the study should be done over, but taken as a starting point for bitcoin, not its starting point which was UNIQUE as being the very first crypto currency, worth nothing, but rather, say, when there were already a lot of coins around, and we can compare bitcoin to the rest with equal knowledge. Say, beginning of 2013 or something.
An altcoin can never start out like bitcoin started out, because when an altcoin starts out, there is already the knowledge that crypto currencies can have value, and one expects the altcoin to have already a market cap.
It would be interesting to plot the bitcoin line, but taking its "starting point" as 1/1/2013, and compare it to the others. I'm sure bitcoin still beats many, but it wouldn't be that spectacular.