It can be the other way round, whatever suits you and give your profit.

If you are an experienced day trader you can make money on both bitcoin and altcoins, so you are only half correct. But it is true that both altcoins and bitcoin are volatile and risky, but that is again true for any other speculative market like stocks, metals etc. So you have to make the decision of watchig the older charts and observing for how long an altcoin actually is able to make a mark on the market. Most of the newly launched ones get washed away in one year while others have been running for quite some time.

In this manner, you can make a decision on which altcoins to buy when you are done buying bitcoin. Your first choice should be bitcoin though.