What would you promote to 10.000 users?

Target: Influencer or instagram active users
Number of people > 10.000

I'm able to send them 1 message (or more) to sell anything I want and they, all, will watch what I'll send. How to make money from them?

Option a = Selling follower to them (I already tried but not much success)
Option b: With CPAgrip try to set one offer but I doubt that they will click.

I have no other ideas. Thanks for your help.

Basically you will have 10.000+ different people in that group. It's hard to give an advice because their taste is probably totally different. Check what products or services can you offer (like what is available or what can you do) and choose that one which is the least special (the bigger target audience is the bigger opportunity).
The other option is to collaborate with a brand or somebody who has the product or the something to sell. You just give the advertising surface and earn the money.

Hiya @Daffy10, I would go with affiliate marketing (CPA), try different offers and see what interests them most (mainstream or adult). Also, there are surveys that you can use to help you understand what likes the majority of the group and take it from there. At the same time I would grow the followers of the group.

Set up a landing page and collect their emails?
You could use the list to spam multiple offers

try to ofer free giveaways items from clickbank
i have some sucess on the past ofering this on reddit

Write an ebook on how they can earn more money with IG, that is right on point. Don´t sell it cheap, and make a pre-order of it, since if it is not that good, they cannot spread the bad things about it and fck your sales up .. sell 500 or whatever limit you want, make it exclusive, then release it .. money in the bank .. ;-)