Is it worth to keep active the blog

Hi i need some help with my deals website!

It has two parts, the deals hub where people post many deals every day and the blog part where i was posting articles about reviews and best products

Is it worth to optimize seo on this website and keep writing articles?

I can't moderate all the stuff people is posting (50+ articles daily) and many time it's duplicate content from amazon and ebay, i think i'll get penalized anyway

I noticed my organic traffic went from 800+ to 10-20
I was ranking for some long tail keywords about reviews, but i got down to page 2 from position 3-4
Is it because of google update or because i'm gettin penalized for low quality and duplicated content?

P.s With the time it takes to write 2 articles daily, i could post 10-20 deals that will reach more people, so i guess it's useless but i want yours opinion too

Thanks for the help in advance

Without blog yours site is like many others - not unique. The biggest and with higher authority sites will beat you at SERPs. Unique and otpimized articles should bring you more traffic and when you decide to sell yours site it will be more valuable. So in my opinion if you are able to write good articles you should to this, as content nowdays is important.

Unique articles with valuable content is what will keep visitors coming back to your site.
And google likes content anyway. So I'll keep at it a while longer. You just might regain
your serp spot.

I agree with you that content is very important ...