No lifeguard is on duty: swim 'at your own peril'. [='at your own risk']
The species is 'in peril' [=(more commonly) 'in danger'] of dying out.
Restaurants that ignore the smoking ban do so 'at their peril'.
(..) for financial gain! The intent is to gain a clearer perception of humanity. Our past, our future, the pitfalls, the possibilities... ...the perils, and the promise. Perhaps an answer to that universal question, Why? I'm all for that. What's wrong with making a few bucks on the side? (..)1989 Back to the Future Part II