It's really simple in FIFA

There's a few tiers of players people like to use

Cheap meta - Militao, Gomez, Inaki Williams, Ndombele, etc
Expensive and not meta - Modric,
Mid range meta ISH - Aubameyang, Griezman
Expensive and meta - R94, Gullit, Vieira,

Going from cheap meta to anything that isn't expensive and meta won't have a significant impact

Going from cheap meta to expensive and not meta is actually a downgrade

Going from cheap meta to expensive and meta is going to cost you 1mil+ per position

A 100k team is better than a lot of 500k teams

What you're best to do is, have a 100k ish team, all your cheap meta players, and invest in expensive meta attackers to carry you, more goals is invaluable, then just get superstar player after superstar player when you get enough coins for the next one