Both ways are need for some basic capital and investitions. To trade you need big sum of money to feel the profit and for mining you have to buy necessary equipment, which is not so cheap, so, you have to look at all pluses and minuses of both mathods to decide what is better to you.
If you are only starting to trade then it's fine to invest smaller amount of money. You can simply buy a portion of bitcoin and use it somewhere or any exchange that you will be satisfied on using it. But in mining, it's the big deal there, you must invest big amount for the mining rig you need in able to earn bigger.
I agree , having a mining rig is not a cheap way of earning bitcoin. It has some requirements first before you can start your own bitcoin mining farm. You need to have cheap electric bills inorder to gain more profit in your mining experience. Electric bills is a big deal when it comes to bitcoin mining.