New coins give those not on the inside at least a chance to make profit. If all we have are 2 or 3 out of a thousand old coins that will pump that week, well, I'm out. That is truly throwing darts at a board, I'd rather play blackjack or the rulette wheel.
That's a daily chart of ALT100USD, an altcoin market index based on value of 100 coins, being traded on Cryptsy. A value is calculated in USD.
You can see that the minimum was 25.139 (Jan 2015) and a current value is 58.65. (+131 %)
So you simply could buy all index components not guessing which coins to choose and have a good profit of the whole portfolio.
Why Cryptsy coins? Because Cryptsy never delists coins (one exception was LGD which was a real scam with an exploit).
Why old coins? 1) not to deal with numerous scam ninja coins and not time-tested one 2) because the pioneers, released before altcoin big bang in 2014, have a value of collectibles, at least.
With a current value of 58.65 ALT100usd still doesn't seem to be overbought. That index was first calculated on January 6, 2014, with a base value of 1000.
It seems since Jan 2015 there is an up trend and probably 1st wave has ended in April.
Interesting graph.. Do you have one that shows the enitre picture? So from January 6, 2014? Would be interesting to see!