You don't really have to finish all tasks to complete the sponsor, i personally don't invest in the youth academy but many people do, but i ussually train players for more than 150% so i din't find those missions very absurd or money traps.

About the 6500 pts in the lucky shots there i totaly agree eith you, wither you get very lucky or you have to invest

Personaly this season i bouht 1-2 levels for 25 tokens each so i could get faster to the 4x association multiplier and for the +1 video in the 3 first videos, some times its cheaper than going for some crazy missions