There are many reasons for this song having 120 BPM telling from its structure. First of all, the drum pattern repeats exactly every measure. On 60 BPM it would repeat twice a measure which is completely unusual. In relation to that, currently every downbeat (by which I mean the position of the big white tick, not Beat 1 & 3 like in the osu! wiki) is equally stressed and more stressed than the other beats, while there would be the same stress on Beat 3 on 60 BPM, which is completely unusual.those wrote:
How do you know it's not snare on beat 1 of every other measure at 240bpm?
Answer: you don't. That's why there is a general way of determining bpm. Need help understanding? There are a number of people that understand; all you have to do is ask.
It's also clearly 120 BPM in the sections where there are no drums, for the exact same reasons. The downbeats have the stronger piano sounds that don't occur in the rest of the measures. The snare argument doesn't work for these sections at all as there are no drums or anything important at Beat 3 here.
What's waaaay less unusual than the exact same drum pattern occuring twice every measure is the usage of snares at Beat 3 to make the song's atmosphere more calm and relaxing. Determining the BPM of a song after the snare pattern is simple and common in osu, but doesn't always make sense with the song.
Also, nobody needs any "help understanding" here, we are talking about a rather complex (for osu!) musical topic that is mostly subjective and there are valid arguments from both sides (although your argument is "the snares must be at Beat 2 and Beat 4" and mine are coming from the song's structure, so they seem more trustworthy to me personally, but oh well.)