The issue is to predict the future, therefore you should always diversify your investments.
That means if some coins you’re invested in going to zero then that event would not affect your whole ICO/altcoin investments.
But, I would not recommend any investment in ICOs/altcoins (however I invested in a bunch of them, but I usually quit when they reach the level I have set) and just a very few are in my long-term portfolio.
ADA is one of them, but diversity, if Cardano fails, helps to survive.
To be frank, this is wild-wild-west, and the crowds (including me as I am not an exception either) behave exactly the same as they behaved back in 18th century (makes sense as we do not evolve as fast as the technology around us).
In addition, to invest in any ICO/altcoin is a very risky, as you cannot predict anything in that space, as the rises/falls are mainly achieved by fooling the people (community) using different tools, as we humans can very easily be manipulated, due to the emotional/instinct driven origin of our species (rational versus emotional).
The crypto markets, as all the other markets (some will argue), are based on an illusion of that market’s community.
The adaption is the key, like in evolution. Never ever the perfect wins, but the most adaptable. (Charles Darwin). I see potential in ADA, but it does not mean that it will win. We will see.