I remember the data was cited along with this guys reports.
https://steemit.com/steemit/@maxg/bid-bot-usage-report-for-04222018
Which as the summary shows, doesn't even support 1 in 3 people using them for the more commonly cited 50-60K daily active users logging in.
This all seems like one of those issues that takes people's focus off doing good on their own and gives them convenient scapegoats, arguments to spend time on and excuses for not building good businesses. While many people continue to do so, despite it all.
I just read this email. And it indeed states that only a very few Steemonians use the bid bots. However the total value of all bought upvotes can be easily calculated. And I did this and come to a percentage of 34% from the total upvote value being sold by bid bots. So I stick to my opinion and think this is a real threat for Steemit.