They 're not doing that for the official trophies.
Any manager who knows how the game works, can make a serial of trebles with the basic pack (contracts, daily log in, a Gold 1 asso group, a monthly card of 5 $ and 20-25 farming vids are enough).
I won 10 trebles in the last 11 seasons (plus a double, lost in C.L. final ).
But I cannot show off anywhere my success.
This is the motivation for those managers.
The top100 is the vitrine.
For many reasons, show off in some local fb groups, show off for "national" reasons, to sell their groups for real money.
The only thing that can stop it is to remove the top100 list and make Gold1 and platinum one division with 50 tokens max prize.
The other way, the hard one, is to rebuild the training with a new system, including the skills -attributes of players and the effect on game play.
Till then, they will continue to find some way.