I'm no expert on drones at all, and no offense to your friend. But if there's interference on one drone it should be there on another, so buying either wouldn't make difference, if I'm not wrong.
Dji spark works at 5.8Ghz, which is mainly used in Lebanon by ISP companies who put their links up via WiFi. And since nothing regulates that, everyone uses the same channel which results in interference. I used to work at one of these ISP and what we did was change the channel of the antenna, to work at a different frequency than the interfering sources, because they all just use the default one.
Another thing I'd say, is that these ISP connections are sort of a narrow tunnel, and are usually high up, at least 8 floors high. So there shouldn't be a big chance of you constantly hitting those "tunnels"
Also the Dji spark, from what I read, has the capability to switch channels, and even switch to 2.4Ghz, which is mainly home router frequencies, not the thing you'll encounter on streets, and definitely not while skiing.
I think you should just compare the features/pricing of both rather than wifi interference. The bepop seems a lot more expensive
https://newatlas.com/dji-spark-parrot-bebop-2-comparison/50545/