I think the thing that resonates the most with me is the roster portion. We spend a lot of time grinding, and opening packs to earn coins, and I can't tell you how many times I've wasted coins in tax buying and selling the same player too soon, or lost out in profits by being to impatient with a card. I think I spent more time being indecisive with my roster this year than actually playing with it and enjoying it. I definitely feel like I've learned the same lessons as you in that I don't need the best players, or even really want the best players if they are all going to be controlled by AI thresholds and animations.

I am doing the same thing as you next year as to limiting purchases to opening night bundle, and Xmas bundle for the presents. Aside from that, grinding and playing is the only way you can be proud of your team, and I feel like I might be more protective of my coins if I feel like they are harder to come by. 

And most importantly, is yes, Don't take the game so serious. I am so guilty of caring too much, and I'm not even that great. I have my moments, and I guess playing too much can cause you to burn out and play poorly in spells so that's my downfall. But I feel this game effected me in more aspects of my life than I ever thought possible, so I know I need to tone it down quite a bit this year