I had the same train of though. I've been using it for years and while I am not sure if it's placebo or not, I can confirm that other music for work I've found online doesn't work as well for me. The "Relaxed focus" playlist is my favorite one.

There is a coupon code for 20% in this review that's still working - https://www.gohomerelax.com/brain-fm-review/