getting (eBook) sales without having a large following?

I've been working on this project for quite some time now, but I really need to make a step forward, dedicate all my time to it and hustle.

youngandripped.net

I have two basic goals now -
1. bring more people to the site - especially people from the target audience, for whom the material is relevant
2. optimise the site to convert as much of those people as possible

Now I have a few different strategies to grow my email list, not sure about the order of importance..
- do SEO on the website
- launch fb ads
- refine my Mailchimp automation emails and offer a few bonuses in the meantime (just give value)
- try to reach out organically to some fitness blogs / youtubers and do guest posts / podcasts
- organically build social platforms (possible without regular content ?)
- actually finish writing the book even without pre-sales and put it on Amazon Kindle (which I am sure without any prior attention or audience I can present it to, in order to get the initial boost of sales and reviews will get lost in the ocean of other books.


Is it possible to be successful without a good following / fans on social media ?
Everybody with a successful online business I was looking at are well established on youtube / twitter / fb / Instagram / snapchat and have blogs with regular content.

More specific, guys in the fitness industry that I follow and who all have their own online products - Kinobody, Mario Tomic, Radu Antoniu, Mike Matthews, Brandon Carter...

Do all of you guys selling digital products have a big audience to sell to ?