I'm new player. ( 1 week only ) so this guides/tips really helped me. some of "guides" is too old , but still useful thx you guys !

so I have one question about player values. I cant understund how it works.

I have two GK. both 18 yers old. one 4* (18) and another one 5*(21) . they dont have special ability and ofc 5* GK is better with stats.

so why the hell 4* GK's market value is 1.2M ? and 5*'s 500k ? can anyone explain ?