What you are doing is correct & very normal. Any good manager has to involve his team and share his ideas with them. Knowledge increases by sharing, you get new ideas from others and you learn. It must keep flowing. If stagnant, it will become lifeless like water of dead sea. When water flows, living being multiply & survive in it but when it remains still like in dead sea, no living organisms survive and the water becomes harmful & useless. As for anyone else taking your position is concerned, you have more chances of loosing it if you heed to the suggestion of your co-worker. If anyone is more deserving of this position, then he will get it anyway on the basis of merit. The best amongst you should be there! Never think of surviving, rather try to thrive and outshine others by your performance. When you grow, others will grow with you as well. If you stagnate, you kill your work station. Then someone else will come in your place sooner or later anyway! And please try to educate this co-worker, that is your another challenge, to remove negativity from his thoughts. He seems to be lacking in confidence. Healthy competition within a team is always good for the organisation.