What's up with these incredibly prolific twitterbots?

Old, highly-retweeted tweets in which I was @'ed keep getting RT'ed by fake twitterbots whose profile photos, bios and names are randomly composited from other Twitter users; they follow each other and spawn at an alarming rate.

It started in January when I posted about David Cameron's plan to ban crypto, and the tweets about that post went crazy and got thousands of RTs. Ever since then, several times a day, my timeline will fill up with newly spawned bots who repost those old, highly rated tweets. They are always brand new, they follow one another, and their timeline consists of other, highly rated tweets. They have random strings for handles, names taken from other Twitter accounts (sometimes appended with an "a"), and their bios and profile photos are taken from other accounts at random, too.

Each one follows several of its fellows.

I have a working theory: these bots are at the start of their lifecycle, and when matured, are meant to be difficult to programatically distinguish from long-established, reputable Twitter users; they're also meant to withstand cursory human scrutiny.

Their creators are mining Twitter for highly retweeted posts on the grounds that those will be self-encapsulated and widely relevant and won't seen like junk out of context. Over time, each one becomes a long-standing Twitter user, with an account full of posts that, from a machine-analysis perspective, look like the kind of thing you expect to see a lot of on Twitter. Each will be following, and followed by, lots of other accounts that fit that bill, too.

But the question is, what is at the end of their lifecycle? Are they just being farmed to be sold on as fake followers to vain celebrities and idiots who buy reputation management packages?

Or do they exist to exert political pressure? Are they hired out to US or Kremlin (or Bahraini or ISIS or…) "soft diplomacy" efforts, suddenly RT'ing a new, original post thousands of times through these plausible accounts to make them bubble up to the top of "what's interesting" algorithms?

What's your theory?

A few bots to get you started:

Elizabeth Jonesа/@iziqavupogoz ["Creatin my Own Paradise Love u Big Bro"]

Betty Walkerа/@oqexuwaz85 ["Political Analyst @Indystar|Mike Pence 2016?|Former @AP, @WashTimes, @WYPR881FM, more|Also @pencewatch2016| tom.lobianco@indystar.com|BigLeBowski"]

Carol Evansа/@oxof_idubegek ["Yolo"]

Michael Garcia/@aday_ozuzuzam85 "[Watch Hispanic Agenda weekly http://wj.la/1nsJ2Tq"]

Linda Wilsonа/@ucuc_ixafus98 ["#1 for Student Satisfaction (NSS). Eight subjects in Top 20 (Guardian). Largest UK campus. Many, many squirrels. Tweets by Alistair, Declan & Kimmy (Marketing)"]