As you know helicopters can fly slow enough to enable the pilot to see ahead. You gave the vis as 1500 m. More than enough.
Well therein lies the problem. When the speed gets too low, you are now in the territory of added controllability issues, an armful of collective, high power settings, and oh by the way - you got here because you couldn't see anything clearly out of the window! This is Swiss Cheese hole alignment 101. When the visibility precludes a safe comfortable forward speed you don't just slow down, you go down and land, assuming you didn't have the basic airmanship skills to avoid the situation in the first place by making a professional decision about the weather before you took off.
Like Crab@SAAvn alludes, when the mission puts you in that situation, you mitigate the risk as much as possible with tactics, techniques and procedures that keep you safer for longer when coupled with the correct equipment and training. To find yourself there for no good reason is inexcusable, and whereas 1500m viz might seem like a summer's day to some (although not many of the professional aviators I know would make such a statement), 1500m is well below what any sensible PPL in a piston single would require for safe execution and completion of a flight for pleasure alone.
It's never about how many limits you can bust and still live - it's about knowing your own personal limits, staying safe, and operating with same level of professionalism and decision making skills as any pilot in any cockpit. PPL's should be smart too.