Why do you need marketing?

The short answer is you need marketing because you want to make money.

I read on an article in Quora a few weeks back that roughly 130k new businesses are born every day, at the same time 120k will stop trading by tonight. That leaves us with 10,000 potential competitors (yes, there could be a remote chance all of the business sell the very same product you do). We both know that it doesn’t even take 2 new businesses to make yours tremble. You could have the best product, superb service and even the 5-star reviews online, but if you don’t market it right no one sees it. If no one sees your stuff, then you don’t sell. If you don’t sell, you grow poor and sad. You don’t want to be poor and sad!

There are 76 gazillion (I might have exaggerated the number) reasons to do marketing listed online but the most important ones are pretty simple:
Sales = Money
Growth = More Sales
Others are doing it. Apparently it is working because they keep on investing on it.

Is that simple, marketing is as part of a successful business as a good location. The sooner you realize this, the more people will see your stuff. If you are doing it right, your clients will become your best promotors.