For steemit: Getting a lot of different phone numbers (which you actually own).
For the steem blockchain: It's not worth it to create hundreds or thousands of bots because it makes no sense. You need to actively vote for good content and as a starter, it's just not possible to have such an effect on your own posts (which could be one reason for bots voting).
It happens on Twitter with phone number?
If you had enough bot accounts wouldn’t you be able to say, age the accounts with off setting your votes for self with votes for good content. At a certain point you could have your own circle of good content supported by aged accounts up voting non aged. Not that it would be profitable, atleast at first. Now if your selling subscriptions for your service that is another story.