A lot of people who know very little about SEO worry about reposting or syndicating content on other sites like steemit. But you don't need to worry. Most of the time Google will know which post is the original. To help Google know which is the original you can add a link in your repost to your original. You can also add this meta tag to the repost and it will not show up in search engines ensuring your original will rank higher.
<head>
<meta name="robots" content="noindex">
</head>
So go ahead, get your content out there to the masses. How else are you going to get people to your corner of the internet?
You can learn more about this here: