This is not exactly gambling and the principle is understandable even for a child, you buy when cheaper and sell when expensive. Nothing is difficult, you just need to catch the right moment.
It's easier when you use bots or make proper plannings with the targets according to the rate every day. If the market doesn't go your way then you just have to hold for a longer time to make some profit. In case of Bitcoins you'll always make profit as the price is increasing gradually.