I sold a gfl for approx 100k dec, I then bought a bunch of summoners for that 100k dec and their value was like 12k dec instead of 75k before with my gfl. it does not work out at all.

I feel your pain, my account is supposedly worth around $1150, im in diamond 1 as well, with a collection power of 447k. even if you took all my cards on the market away from the value its still over 1k USD value but cant get past diamond 1....