The problem as I see it is guessing which altcoin will succeed. I was looking at the historical charts from coinmarketcap in 2014 and a lot of the top altcoins just crashed hard. Ripple is about the only exception and I never really saw it as a true crypto. It is heavily centralized with a huge premine. In fact, I would consider Ripple to be more like a bank stock. I also felt there was a good chance that the SEC would (and could) shut it down.
Next possibility might be Litecoin, but that coin was up to $50 at one time, if you bought around then, you still haven't recovered, much less made any decent profit. I bought a few at about a $1 each, sold them when they hit $5. Used the profit to take my family to McDonalds.
Using the chart from Jan 2014, this is what I see (numbers are heavily rounded and not exact):
Peercoin, the #4 coin with some good ideas, went from over $7 to around $2 today.
Mastercoin, the #5 coin, seems to be gone now. The link takes me Omni...not the same coin unless they are destroying coins by mining.
Nxt, the #6 coin, survived okay, but you would have still been better off leaving your money in bitcoins.
Namecoin, the #7 coin, went from $7 down to $2
Bitshares, #8, from almost $20 down to $0.08, ouch
Quark, #9, from a dime to a penny, I guess the Bitshare people think you lucked out.
Megacoin, #10, from a dollar each to a dime each....
and you see failure after failure, at least the Dogecoin people have their memes. And if they wanted they could change their name to Wolfcoin, change their emission rate to 1% per year (down from 5%) and succeed if they got together (they won't, but a rich strongman could force a fork and make a ton of money).
I scanned all the way down to the last altcoin (#67) and there isn't a single one that I can say "oh, I should have bought that one".
It isn't till Darkcoin (Dash) came out in early 2014 that I can see a decent investment show up. Even the instamine seems to be doing more good than harm. Speaking of stealth coins, how the hell did Monero get anywhere? I downloaded their wallet and it just opens a DOS window with a CLI. There doesn't even seem to be a help menu. I imagine 99.9% of the Monero people are storing their tokens on an exchange.
Ethereum in late 2016 would have been a good bet, but personally I felt it only succeeded because Bitcoin is in a civil war over scaling. Turing complete (and yes, I totally understand it) sounds really cool, but I have always felt that cryptocurrencies true strength is as a store of value and censor proof transactions.
There have been a few bubble coins recently (STEEM, GOLEM, STELLAR), but if you invested heavily in one of them, you were probably doing a shotgun approach or got very lucky.