@louisthomas asked that question in one of his posts: "Is Steemit Just for Popular Content Creators?"
Well, I feel like I am a good example of how you don't have to have an existing audience to succeed quickly on steemit.
I joined June last year and made my first post early July. I did not know a single person on steemit, did not know of any chatrooms or discussion forums, had no audience on any platforms (apart from 400 followers on twitter, lol), and did no external outreach. Yet, my introduction post got 336$ worth of upvotes at a time when STEEM was well below 2$, 1,060 views, 333 upvotes and hundreds of comments since gone on to obtain a reliable size of upvotes on my posts ever since. All of this is completely unheard of for any traditional social media or blogging platform. There would be no way to get such traffic without lifting a finger, but instead letting the platform and community do its own thing, and it would take months to achieve a similar level of monetizing and regular following.
I then went from 0 to 400 Followers in 3 weeks, again without anything but the organic growth of engaging with steemians and receiving upvotes.
Now I feel like I have established myself well and hope I can contribute to taking the platform to the next level to compete with mainstream alternatives. I may not hit the trending page at all times, but occasionally which means I'll have periods where I get a fair amount of new steemians finding my content.
All it takes, imo, is showing the determination and desire to make valuable contributions to the Blockchain and the platform, which may come in many different forms. Finally, there is certainly something in steemit also for those who are not "Popular Content Creators", but simply making positive engagements with others and contributing to fruitful conversations. At least anyone who does that on my posts are guaranteed an upvote from me. So if you struggle to get seen with your posts, spend a bit more time engaging, positively, in comments on posts that get a lot of views and gain traction that way.