Their is no way to get followers with useless content, it's so foolish that some people are trying to gain followers through some tricks while their content is not good.
Most probably you have listened that content is king because instagram's algorithm is getting smarter day by day.
Yes, this is is absolutely right.
So what is use of this ebook and all the people who are trying to help you gain followers?
Are they useless?
Answer is absolutely no.
The point that is missed by alot of people is, Representation of content.
Representation of content, do affect your followers.
Maybe you have experienced the situation where you cracked a joke and no one laughed but when the same joke was cracked by another person, everyone laughed.
The same thing is happening on Instagram, where the one thing you presented doesn't reached a lot of people but the same thing when presented by someone else, got viral.
So it is more about psychology of people rather than Instagram algorithm.