Irony of any job seekers: When you want a job, you cannot get it. But when you find a job, you do not need it then. Unfortunate. If you are satisfied where you are and your boss supports you, there is no reason for a change but this is when all these calls happen.
Always remember, in a free world, you cannot be locked in forever. And when it rains, it pours. Realize there are no such thing as a bad situation, it is you who has to create outcomes based on whatever situation gets presented to you. Keep the faith and be positive.
Yes, you would see a lots of recruiters who do not respond back and this speaks a lot about the company you want to join. Yes they do get lots of profiles but there is no harm in sending a note as a process for everyone who applies(remember this can be automated as well).
Make the best of what you have at that time