Concentrating or Diversifying your investment portfolio?

Endless debate or advice from Gurus or FAs!

Why concentrate must be Verb and not Noun?

Read? Portfolio Management Concentrate (Verb) or Concentrate (Noun)

For investment portfolio management; many Gurus are advising retail investors not to concentrate (Verb) as it is very risky since most retail investors don’t have that level of competency to concentrate (Verb) yet.

But; for Uncle8888’s portfolio management it is currently concentrate (Noun) with a few freehold core holding and a large war chest. How risky?

Concentrate as verb or noun?

See any difference?