I'm a practicing polyamorist and have been for years. I've been surprised at how many of us there are who identify as poly! I certainly understand why it wouldn't work for everyone, but for me there is just no other way to be.
I like to say I'm a work share program.
For a very long time I didn't know about poly as an option, and found myself in a series of monogamous relationships that never lasted longer than six months! After my marriage (three years, but we had kids, which complicated decisions), I found the poly community, and most of my relationships have been the longest and most fulfilling of my life, some still going strong coming up on the two plus year mark.
I'm just not happy if my options to love are limited, whether or not my sexual options are. Open relationships are great, but even they aren't enough for me. I need to love equally and fully and frequently to be truly happy.