Even when competitors realize your idea is good, (a) it will take them a long time to implement and (b) they’ll probably screw up critical things.
And finally, working on your ideas will lead you on to new ideas. So you’ll be a moving target; by the time competitors copy what you’re doing now, you’ll be doing more.
Worry most about how to make something people want. If you’re building anything good enough to copy, you’re way ahead.