Buy altcoins at low price and sell at high price
Too risky. He better to buy bitcoin, although he only hold bitcoin untill the price up, this way is profitable enough. But he still need to control his emotion, he must believe bitcoin and don't be panic selling when the price fall
If you choose the right altcoin, there could be big profit.
It's like a bet, if you place your money on the right horse, you'll be making tons of money.... But the great question is -- which of the hundreds of altcoins is the right one? Too many shit coins to choose from, but people mostly tend to choose these over the coins backed by real developers as they offer more volatility. As always, it's greed that is taking over common sense. It's pathetic.