Brand building is the way I go. my sbi site is my author homepage. I don't think an author site is going to bring in much income from ads; I think it's more about having a place for readers to look you up and find out what else you wrote, so more about marketing yu books, then gaining income other ways.
What do you want to become?
I am the same way writing first; site second. However I make sure to add at least one new page to my site each week, with a goal of one a day. Usually what I find best to do, set aside 1 day to do my sbi site.
I do my writing as a business. I set aside 8 hours a day to write/edit/format/design covers/etc. So I have 4 days of writing 8 hrs and 1 day of web page creating for 8 hrs. usually I can created 3 to 7 pages during that time.
Even recipes for food mentioned in the books. (This has resulted in 400+ pages)
I also have pages
I do this as well. For example, I write fantasy, so I have an entire section on "Fantasy world building" , with a page on culture, one on planet building, one on religions, one on plants, etc(about 40 pages)
Because I write a lot of short stories, I have several pages on writing short stories.
A year ago one of my series got hit by Amazon Adult Filter and I got then back online, so wrote a page on how I did it.
A year before that one of my books got attacked by an author who created 52 fake Amazon accounts so she could create 52 fake 1-star reviews on my books, and so I wrote a page about that.
I figure, I'm not the only author who had these things happen and so I should write about the experience and share how I dwelt with them, so that when other authors run against things like that, they could have a reference for what someone else had done when it happened to them
I try to keep a record of everything I do in my writing career and share as much of it as I can
In total, there are 784 pages that I have been able to create so far, just in yapping about myself, my characters, my experiences as a writer, and my books.