Let's say I invented a genius way to use cryptography to send anonymous payments, I'd go to jail for doing that (Tornado Cash). Let's say I made a secure messenger, I'd go to jail for that (Telegram, EncroChat, SkyECC) or narrowly avoid jail (Session) or be forced to add a backdoor (Anom). Let's say I made an operating system that didn't spy on you, I'd be threatened with jail for that (GrapheneOS). And of course there are more things, for which there will be more consequences (mostly jail) but for things that haven't been done yet there are obviously no examples offhand.

Basically everything that fits outside of existing patterns is illegal one way or another. Only people who are naïve to these consequences will ever be motivated to make these things.