How many soccer parents will drop $9.5K in a lens? I suspect very few.
Very few indeed.
In Germany, I have made an interesting observation, specifically in soccer but also in handball (which is huge here btw)
The more serious kids participate at their chosen sport and the more cameras and distinguished lenses you'll see at soccer games or at the complex where a tournament is held.
At the lowest level, in Germany we call it "Breitensport" (roughly translated "mass sport") most parents (age group 10 - 16) basically do all their photos with a smartphone. The quality of the photos is quite bad (if I am mean I'd say it reflects the level of playing/ competition).
Starting U12, this where most professional Bundesliga teams start with their own youth teams, you'll see 1-3 parents who invested in a DSLR/ DSLM with a medium tele-lens such as EF 70-300mm or RF 100-400mm.
Looking at the "NLZ Sonderspielrunde" (basically organised friendly games/ small tournaments between youth teams of pro soccer clubs) you'll even see some white lenses such as the 100-400mm.
At the big U13 tournaments you'll see parents of every team taking pics with quite professional cams and lenses. And even some clubs have their video analysts film the game (usually from a fixed tripod or "coaches eye" spot that covers the entire field) and have them shot photos while the cam films. Mainz, Stuttgart, Bavaria Munich hired a pro who takes pics with EF 300mm/ 400mm prime.
Going further up, U15/ U17 pro level, you'll see at least two parents with a pro camera and a white or big white lense. Furthermore, the clubs might have a photographer there as well, so might the DFB (German soccer association).
So, in conclusion: When the level of competition rises, so do the efforts of the parents in order to make memories out of them.
For the RF 100-300mm F2.8 there are only very few parents who will pay for that lense. Given my observation, I'd guess:
There are 57 "NLZ´s" (English: "Youth performance center" --> youth teams from pro soccer clubs)
subtract those from financially challenged regions and the NLZs from lower leagues (level of competition is lower as well) and you'll end up with app. 25 NLZ´s- Each NLZ has four to five teams. If all teams have one parent who'll purchase such a lens it gives you around big white 100 lenses in total. Considering, that these lenses are sold over the years and some parents/ teams already have bought big white lenses, I'd guess no more than 6-10 RF 100-300mm F2.8 lenses are sold annually to soccer parents/ pro youth clubs. This is just based on my observations, not based on data.
For Canon, I'd try to specially target parents, who fit the bill in the RF 100-400mm price range/ area. This lens and the R7 is a good start.
