It is ok to decline a recruiter. You can't take all opportunities, and are going to have to decide which one to take.
There will always be opportunities, as long as you keep working on yourself.
- Thank them for their time.
- Leave it open, that this opportunity doesn't interest you right now, and that you might reach out to them in the future.
- At the moment (March 2019), the growth is really happening in Indonesia
- Easier to find rocketship companies there
- If you want a better salary, and better opportunities, go to Singapore