The number is real, but seasonal. The valley's 72 waterfalls are fed largely by snowmelt, so the count you'll actually see depends on when you come: May to early July is maximum flow, when the cliff walls genuinely stream on both sides; by late September many of the smaller falls reduce to threads. Two are worth planning around specifically. Staubbach Falls — the one behind the village church in every photo — drops nearly 300 meters in a single free fall, one of the highest of its kind in Europe, and it's free to walk to (there's a path behind the spray in summer). Trümmelbach Falls is the oddball: ten glacier-fed falls inside the mountain, carrying the meltwater of the Eiger, Mönch and Jungfrau — up to 20,000 litres per second — reached by tunnel lift and galleries. It's the only one with an entry fee and the only one worth it in any weather, since you're underground anyway.
Do you need a tour for the waterfalls? Honestly — no, not for the famous two: both are reachable by valley bus or a flat walk from the station. The 72 Waterfalls e-bike tour earns its price by covering the full valley to Stechelberg — the stretch most walkers never reach — with a guide who knows which falls are running that week. If you only have two hours, walk to Staubbach and take the bus to Trümmelbach. If you have half a day, the e-bike shows you the whole amphitheatre.