For most people, buying Twitter followers is as pointless as purchasing Facebook friends. What's the point in tweeting if your thousands of followers are but slivers of empty data? No one's going to read it. To begin the outlines of an answer, Twitter has to be placed in the cultural moment. Twitter is the social media platform par excellence for the narcissistic self. Your Twitter account is the ultimate selfie - the number of followers one accumulates read as a crude measure of your "fame" and/or amount of social/cultural capital you possess. For instance, sticking with Our Justin, his celebrity and 46 million or so followers very roughly correlate. Likewise, the Bieber-esque Bolshevist Owen Jones with his 161,000 followers more or less represents his prominence in our curious commentariat subculture. Yes, follower counts can be easily gamed simply by following thousands in the hope that follow backs see you rake in similar numbers. That's why, darling, follower/followed ratios are a better measure of "authentic" Twitter fame (mine's 8.3, in case you were wondering).
Hence Twitter followers signify something. They signify a capacity of a tweeter's words to fall onto thousands and millions of feeds, which in turn will be picked up by thousands and millions of eyes. Follower counts mark one's place in a hierarchical social universe constructed subjectively by each and every tweeter which goes beyond the usual measures of taste, of whether one likes someone or not. It stands to reason then that the top 100 lists I do every year map out a section of the social space I engage with as a tweeting politics blogger. These posts prove popular by the standards of this blog because many tens of thousands live their social media in the same space and are interested where they and/or their favourite writers/hate figures, friends and rivals figure in the unspoken, unmapped pecking order.
Outside of Twitter this doesn't mean a great deal, really. Followers are just numbers on a website. They won't help you pay the bills. It's not going to give you your dream job. Is doing well on Twitter just a case of illusory influence?
More important than the Twitter counts is the "quality" of the people following you. You have 2,000 followers from the four corners of the globe? Nice one, pleased for you. Yet if you have 200 in tow, and they're disproportionately big political hitters, top commentators and bloggers, well, the better chance there is of converting the "capital" represented by your followers into something more tangible. A retweet from Polly Toynbee or Boris Johnson might lead to more followers, and/or greater numbers checking your writing out - assuming you have a blog appended to your Twitter account. Or, even better, you'll have movers and shakers reading your work. Some might ask if you can do some bits and bobs for the New Statesman or Comment is Free. And if you're really unlucky you could be approached by The Huffington Post.
Most people who want to make their way in Commentaria will not be in that position. And even if you are followed by "celebrity" tweeters, chances are they'll miss your output as they focus on the doings of their nearest friends, or answering the scores of replies that come in every hour. How does one make a splash? One way of doing it is becoming so big that one cannot help but notice you. If Twitter followers are a crude measure of social capital, and capture in a very rough way one's standing in a particular subculture, if you can build a five-figure following future growth becomes almost self-sustaining. Political people notice that someone has a big following, reason they're worth a follow on that basis and duly do so. This is especially so when politics folk tend to follow others with the same views - one can, whether they wish to or not, present as a "player" in that specific context. Accumulation is then self-sustaining and before you know it, hundreds of people might be retweeting your comments, witticisms, graph or photo. And if one goes truly viral, it might get the attention of someone looking for a hip, young gunslinger to fill a slot in their paper's blog, or whatever.
When you buy Twitter followers, it's not about fooling yourself that you're popular. It's about the social milieu you wish to make a splash in and aim your activity at. It's a strategy that inflates your apparent importance, acts as an attractor to others, and can help - theoretically - establish you as a somebody without a campaigning record, a ream of original writing, or insightful tweeting behind you. When someone buys thousands of zombie followers, what they're trying to buy is standing.