I don’t care where people buy their books–indies or B&N or Half Price or online or Urban Outfitters or Target or the airport or your neighbor’s stoop–I just like it when people buy books. Yay, books!
With one exception: buy it where you found it.

If you discover a book in a bookstore, buy it there.

There have been a lot of trend pieces lately (and this article) about people using bookshops as showrooms–browsing the display tables and staff picks, then jotting down or taking pics of the titles to remember to buy them from an online retailer. I say: that sucks! Somebody working at that bookstore decided to stock the book, and liked it enough to put it out for you to find it. If you wouldn’t have known or thought to order it online without seeing it in the brick & mortar store, that store (and its helpful curators, the employees) deserves for you to buy the book there. Even if it costs a dollar or several more than online.
By the same measure: if you discover a title from an online giant’s email or newsletter or algorithm, great! Go ahead and buy it from them.

But a store is a store, not a showroom. It’s there to sell things and if it doesn’t, it will go away. Now that we have online retailers with no physical presence and mobile shopping apps up the wazoo, we have to protect the brick & mortar stores that help make our towns and neighborhoods vibrant places. Unless, of course, you want all the businesses around you to be banks and cell-phone stores. Nothing against them, but personally, I’d prefer a few bookshops in the mix.