That secret is vote buying. There are bot-operated Steem accounts that have very high Steem Power and that accept transfers of STEEM or SBD as payment for upvotes. The profitability of using bid bots is questionable. In their competition over Steem Power delegations, it is the delegators (and the bid bot owners) who earn from bid bots, not the vote buyers.
Bid bots are best thought of as promotion tools. If you want to promote your posts to garner attention, then you can use bid bots. But they are no shortcut to high earnings as you generally pay for what you get and sometimes more. One constructive use of bid bots is for projects to make important announcements because by paying enough to bid bots it is possible for a post to get to Trending. A lot of Steemians do not think very highly of Trending as they see it as being filled with highly rewarded mediocrity or even trash. Whenever a scammer appears on Steem, they are inclined to use bid bots to gain attention to reach potential victims.
If your question is about number of upvotes, say for example thousands of upvotes, that can be easily get-able with the use of instant bots like smartmarket and minnobooster.
If you are talking about thousands of earning, then again that can be get-able with the use of bid-bots and instant bots both- People are using high size bids to get the greater pie of the bid bots and that is boosting their post the trending page of steemit.
If your post is in trending page then you can get the attention of public in steem community as most of the people definitely check trending page once in day at least as far as I know. You may also get some organic upvotes from the whales if your content is interesting and good.
Thank you and Have a great day.
Here is the one line answer :
The same way some FB posts get thousands of likes , either by money (promotion) or quality of post or by network.