Valens.......it all depends...
is it your dream: Go for it. When I was an instructor , I had students from different backgrounds and ages and most of them said flying helicopters is the best thing they ever done. (and some of my students had an awesome life). With a PPL you can have great fun flying and improve your skills next to a normal day job.
is it for a career: 31 is not too old for any career, fixed wing or helicopters. But if you're aiming to get a good pay out of it, then fixed wing without a doubt.
The investment in a fixed wing career is cheaper, the outlook for a job is a lot better and the salary is a lot higher. (but flying is not like flying a heli of course).
The investment into a good heli career means PPL-CPL- twin type rating and IR (~100-125k) and then if you are lucky get a job with a very average salary. Which will grow of course but it will take ages to pay of the investment you made.
Having said that, some people get lucky and get a good job with minimum hours etc.
A different route is PPL-CPL-FI (~70k) where the investment is a bit less than the IR route but the salary you will get is also less. With a good company you might grow into different types including twin engines.
In short: are you in it for money, fly planes. is it what you love to do, fly heli's. Money can't make up for that smile you get on your face each day you fly a heli. Although I can imagine a BA captain looking at his bank account might create a bigger smile........
Best of luck with your choice.