[tedmiston]

Tons of Instagram users use it for "serious" photography. Perhaps you don't follow them, but many do, myself included.

https://www.instagram.com/1st/

https://www.instagram.com/dariusaskari/

https://www.instagram.com/msalisbu/

https://www.instagram.com/tiny_teaa/

I would even argue that Instagram has in some ways redefined professional photography (by enforcing different constraints than a professional photographer is used to).

Aggregator accounts are one of the best ways to discover high quality users.

https://www.instagram.com/nycgo/

https://www.instagram.com/cincybaton/