If what you’re saying is simply to double your current bitcoin holdings then I would say it is the best and less risky option. It is true that Alticoins have tendency to grow in higher percentage than bitcoin during the bull run. But the risk is higher because most of these Alticoins could just dump anytime but with bitcoin one is guaranteed a cryptocurrency coin that is a store of value and also a ROI. Also almost every increase of the entire Alticoins depends on the percentage increase of the bitcoin.