I keep low key because I have a job and I focus on writing.
Now as for the marketing, that has to do with audience enlargement. Many traditional writers go out there and have speaking engagements and a traditional publisher takes care of that (look at the Jordan Peterson publicity machine). If you are independent, like me, you can Go Big on social media, blogs, etc and make it $$$.
Some great writers get caught up in the marketing and drink their own publicity kool aid and lose their writing 'mojo' like Truman Capote. Some great writers just write- they would like to be known for their work but sometimes they don't get recognized in their lifetime The great Italian novel "The Leopard" for example.
With the technology of the iPad (THANK you, Steve Jobs) and publishing (Gracias, Lulu.com and Smashwords.com and CreateSpace/Amazon) and free ISBN (Merci, National Library of Canada), , I am pretty much...a one-woman publishing machine and I write what I want and put it out there. Sort of like the late musician, Prince
At my age, with my variety of experiences, and my own track record, I publish whatever I feel like. Reader feedback is important and in the Amazon world, feedback by purchasers is seen as more credible.
Nevertheless I don't let a poor review devastate me (that's very drama queen, isn't it?) - some people will actually give up just because of feedback. That does the world no good.