Can't judge if it is fake clubs that buys the highest level trainers but what is very obvious is that these clubs surely can't be too successful either in short term or long term due to such trainer. I don't think it can ever be economically defensible to buy a level 7 trainer due to the very high price and salary. These trainers must be dominated by farm teams. I very much doubt that BB really likes farm teams. I don't think that they are within their interest. That you organize and get a good plan for training a player and during those seasons perhaps do sacrifice your team to some extent is one thing but farm teams ruin their economy without building a team.
But sure if you train 3 players genuinely you can get 6-7 million in total when you sell them 7 seasons later and for such money you can buy a rather good team ..