I'll admit it--when a recruiter approaches me, I always listen to their opportunities.
(Sorry boss...!)
That doesn't make me a disloyal employee.
I'm perfectly happy with my company, but listening to new opportunities allows me to make the informed decision that this is the best company and position for me right now.
If I don't listen to other opportunities, I don't know what I'm "worth" in the market, or if there's a company closer to my house, or with a culture that suits me better, or with a step-up that I hadn't considered.
By listening to new opportunities, I choose my company every day.
By not listening to new opportunities, you're giving your current employer too much power.
You're assuming they're paying you what you deserve
You're assuming they'll promote you when you've earned it
You're assuming the way they do things is the best way for you
You might not be open to new opportunities, but I can guarantee your company will always be open to new employees.
Keep yourself informed.
PS: Article shared by one of my friend on a social channel and I loved it. Couldn't find the reference yet. Hope you like the article!