The Altcoins are designed to enrich the creator, plain and simple. BTC may have been designed for that purpose as well, but at least it was extremely innovative.
Not every creator pre-mines their own coins, those are the alts you should steer clear of.
2nd you should avoid buying instamined coins early because they are usually dumped to hell as soon as they hit an exchange.
Doge is an anomaly in that it is a piece of crap coin but ppl are still buying it.
It violates all the rules of being a good coin.
1. Instamine
2. High block rewards/hyper inflation
3. infinity coin production
Basically stay away from alts like doge