That gave birth to a very lucrative business in selling Facebook Likes and Twitter Followers. As promising as it sounds, there are many reasons why it is a waste of money in the long run.
1. The accounts used to Like and Follow you are usually automated bots that add and delete thousands of friends at a time. Most of the time you will lose those likes/follows in a week.
2. All of the fake accounts significantly drop your Click-through-rate to links if you use sponsored tweets or similar network. Advertisers will know if you have legitimate followers or not.
The really only best way in my opinion to get Likes and Follows is through exchange websites where you earn credits for Following people and other people follow you in return. Even then, a lot of people end up UnFollowing you if they aren't interested.
That's why instead of wasting all this time and money trying to Buy Followers you could be providing interesting Content, tips and Media that people will actually Like and Share.