i think both is good, you can earn some money from mining then you can trade to at the sametime,every month your income from mining can be capital for trading, because if you just trading you can lose sometime, in mining you can income everymonth althoguh the result are not much.
No is not, if you are not good on Trading you could rely on mining, it is a passive income where you are going to buy expensive hardware to do the work, all you have to do is to maintenance your mining equipment and enjoy everyday earnings. Trading is like an easy profits everyday if you are good enough to analyze everyday's altcoin graph to predict what to trade or when to trade.