Why alt coins are good for trade ? why not bitcoin ?
Because alts has higher chance of gaining more income than Bitcoin when it comes to trading. It is faster in terms of price increase because alts can be easily hyped and manipulated to the market and at the same time it can be easily dumped. An altcoin can increase a 100% easily and when you trade it to bitcoin you'll have a better chance at earning more profit.
Whether it is altcoins trading or bitcoin trading, both can be really beneficial if the trader has got necessary skillset. But I also think that bitcoin trading is far more beneficial than altcoins trading when it comes to profits. The most important thing that is required to make profits possible is volatility and a noticeable change in the value. Bitcoin is best in these. A trader can make money during pumps and dumps. Not only this, day trading can also return big amounts.