With 99% probability you're buying your own bullshit and you don't really have anything worth protecting. Inventors routinely overestimate their own cleverness and the significance of what they do.

In the 1% case that you actually have something (0.01% if it is a software "invention")...

If it can be reverse engineered, through use or observation of any application, patent it. If not, keep it a trade secret. Pick employees carefully and make them sign an appropriate NDA. Most investors won't sign an NDA before talking to you, so if you need money to do a patentable reduction to practice, you're in a chicken-egg bind. No easy solution. If you can't figure out a full pitch with a demo that doesn't reveal everything, you have to find money some other way.

You can usually figure out an IP lockdown one way or another even if you can't patent the core. The more you spend, the longer the lockdown will hold. Your question is really how much risk reduction you are willing to pay for.

Chances are, unless you've discovered a cure for cancer (in which case consider being nice and giving it away) or anti-gravity, IP-theft risk is likely not even in the top 10 risk factors for your business.

Your paranoia is probably self-importance and/or a persecution complex in disguise. I'll bet you $100 if you just released your "invention" open source or as a defensive disclosure, something amazing will happen: absolutely nothing. You'll have to do some marketing even to get people to take your invention for free.

In other words, statistically speaking, *any* amount of paranoia is too much paranoia.