They tend to be prohibitively expensive and, moreover, are usually at the wrong point in their development to represent a sound long-term investment (unless you’re lucky enough to bag them one of them on a Bosman).
The majority of players in the 85+ “world class” tier in PES are great if you’re playing straight online head-to-heads, M圜lub, or other game modes, but aren’t the players you should (or even can) acquire in Master League careers.