It is very easy to increase bitcoin, just by it with your cash.
I think he is referring on how to increase btc by means of working with it not just by buying. if you already have capital, better try how to trade but make sure to educate first yourself on how things work. its not going to be easy and also risky but give it a try. if you became a good trader you will earn for sure.
May be, he wanted to say that, Buy bitcoin with the low rate and hold them until the rate increased. Its the main rules of trade. Agreed wit you, For starting the trade, First you have to well educated about the trade. Do your own research about coin/currency. Then start it. Don't follow everyone But try to learn everyone.