How do you share startup ideas without getting burned?

I had someone take a concept I shared in good faith and launch a lazy clone of it a few weeks later. The silver lining was watching them struggle to execute because they didn't understand the 'why' behind the design decisions. But the trust hit was real and it made me want to build everything in total secrecy.

Moving forward, I started sharing only the problem I'm solving rather than the exact how at least until I have a working MVP. For founders who've had an idea taken how do you set boundaries with collaborators without becoming completely paranoid?