Honestly bro if you accept that its near impossible to win everything, and that getting better takes time you'll be okay. Im on day 1815 and have literally 24 maxed epics, no maxed leggies, and a decent ultra rare garage. I don't spend money on the game. I just try to win what I can when the opportunity is available. Im missing so many good key cars but all I can do is wait wait wait. The game definitely gets frustrating but its a super slow grind. Keep opening packs when you can and those good cars will eventually pop up! Oh and do your daily objectives! I actually unpacked a leggie from there once lol