Refurbished electronics aren't inherently less reliable than new ones - it really depends on what "refurbished" means in that specific listing. Amazon Renewed items can range from stuff with minor cosmetic damage to units that were returned and tested, and the description should tell you which category this laptop falls into. If it's been properly tested and restocked, the hardware itself is usually fine.
The thing that matters more is what happens if something goes wrong after those 90 days. That return window is solid for initial problems, but once you're past it, you're dealing with whatever warranty the refurbisher provides - check if that's 30 days, a year, or nothing. Compare that to what you'd get buying new. A 30% discount doesn't feel as good if you lose warranty coverage for most of the laptop's useful life. I'd look at the fine print on what's actually covered and for how long, then decide if the savings justify the shorter safety net.