Why even submit a preprint? Here is a list of six of the benefits:

1. Career advancement. A preprint provides funding agencies and promotion and hiring committees with public evidence of your research productivity and most recent accomplishments, which is pertinent for their decision-making.
2. Establishing a record of priority and attribution of credit. Preprints are the main mechanism for disseminating research earlier, establishing priority in research and attributing appropriate credit. Establishing priority also protects your research from being ‘scooped’.
3. Improvement through feedback. Colleagues, peers and other scientists may contact you through email or through commentary on the server and give you feedback. These types of interactions and feedback are educational and can help you to improve your final journal publication in addition to the scientists who formally peer review your final version of the paper.
4. Rapid dissemination of research. Preprints allow you to share the results of your research earlier and rapidly and when you are ready to do so.
5. Visibility. Your research is freely accessible globally, without requirement of subscription or other journal-imposed pay wall. This allows for developing new collaborations earlier. Once your research is in the public domain, new interactions can occur which can advance your work or lead to new collaborations. Visibility of work also promotes invitation to meetings (meeting organizers are often looking for recent work not published in journals) and helps with your personal branding.
6. Citations. Infrastructure providers like CrossRef link the final published article to the published preprint whenever possible. Because of the increased visibility, preprints show a significant increase in Altmetric attention scores (which capture mentions in news and social media), which also leads to higher citations in the scientific literature.

More reasons to take the preprint plunge are outlined here:

Ten simple rules to consider regarding preprint submission
Bourne PE, Polka JK, Vale RD, Kiley R (2017) 
PLoS Comput Biol 13(5): e1005473
https://doi.org/10.1371/journal.pcbi.1005473