It's quite clear, downloads are a number one metric of appreciation on SoundCloud. Imagine the moment of people downloading your music, why do they do it? Most likely they would like to save it on their phone or a player and add it to their offlie playlist. Isn't it the result most artists dream of? If a song gets many downloads, it gets spread socially right after it. Many other people would be able to hear your song with your visitor which downloaded it and now has it in his or her player. After the download your tune is going heard by many, in caffes, fitness centres, shops and bars, on home parties, it will be shared with friends, mates and relatives. This is is great - it can get much more downloads and become viral this way. So, now the answer to the quesion "why do people buy SoundCloud downloads on their songs" seems so easy: they do it to create a better image for their music and to try starting that sequence of getting famous. This boost is cheap and effective, so why not doing that?
You can try doing it with two ways. The first is doing all organic promotion by taking advantage of advertising channels on various online and offline platforms and so getting only natural plays. And the second one is to buy downloads and other boosts for metrics on your songs on SoundCloud. Both ways are effective and show a good result but you need to understand how to do your marketing the right way. You can find an agent or even an agency to start promoting you and your music, but it's going to be quite costly. Or you can start learning from tutorials and contact our managers on how to get more SoundCloud downloads, and then ask them to assist you on creating your first marketing campaign. It would take you time, but it's going to be way cheaper and you might find out many things you didn't know. So it's up to you to choose, as always.