I've bought many scout players , aswell as regulars. To win champions cup and the league, your team HAS to be stronger than the average team in your competition league. Since in champions league aswell as the cup you can find yourselve competing vs, teams 2 or 3 leagues up. I have maneged to win some champions league , no cup yet , as in the finals i tend to meet managers with way better teamquality.
Financially, the further I get in the league and cup, the more revenue, enabling me to earn more. Winning it is secondary, realisticly I dont expect to win either. However, managing this way, has given me a couple of competitions and champions league wins, and got me way further than expected in the cups.