The sad part of this, is that most of that money goes directly towards identifying & then training high performance athletes. Very little of it goes back to grass roots, to build swimming pools, gyms, athletic tracks etc etc that Joe Public, or regular sports loving kids can benefit from.
There have been legacy studies done on the participation rates in Olympic sports, before and after the London games. There hasn't been any major change, despite all the high profile success stories, brand name athletes & PR spin from the likes of Seb Coe. That's really sad imo & a very poor return for their money over all.