Do yourself a favor and go read a book about currency markets and basic business practices. Have you ever heard of the Euro? Do you have any idea why they created it? I will give you a quick answer (one of many, but this reason is relevant to the present discussion): because Europe is millions of people of different cultures living very close together and having a dozen freaking currencies milling about was a TOTAL PAIN IN THE ASS. So they consolidated all that mess into 1 currency to make things easier.
Muahahaha, a professional economist talking, eh?
The Euro was introduced to eventually force a political and fiscal integration of Europe into a super-state. And because politicians are full of crap.
There was no solid economic reasoning for introducing the Euro and many economists warned and still warn about the risks of instability that the Euro causes.
Transferring this reasoning to altcoins: an altcoin is viable if it is
different enough from other coins (e.g. confirms are faster) such that it could have a
different use and market. Most of the new ones are worthless.
As I noted, there were a myriad of reasons for the Euro and I won't get into the politics of it, but to say "there was no solid economic reasoning" is a bit dismissive. The economic reasons were reduced transaction costs across states and easier cross border investment and trade. Theories dealing with currency aggregation in regional areas date back to the 1960's. The Euro may be unstable and/or a stupid idea in practice, but there does exist valid theory behind it. And as a bonus, when fat, rich Americans travel to Europe they can cross borders will-nilly and spend their Euros like they never even crossed state lines. Just imagine what economics in the US would be if every state used its own currency.
As far as altcoins go, sure they may be
viable if they are different enough, but viability does not mean they will ever be worth "real" money or possess any trade value.