If that portion were being shifted with no compensation to the am player, you'd have a point. But if the amateur player is paying $40 and getting $40 worth of product (or, say $20 worth and the opportunity, with good play, to win more than $20 worth of additional product), how is that player's experience diminished?
I guess what I'm bumping on in this discussion is why anyone else can add money to the purse via sponsorship, perhaps through selling a product to raise funds, but when the TD/club does it, it's somehow robbing Peter to pay Paul and wrong. If the club were selling CryZtal Buzzzes as a fundraiser for the tournament, would you insist on only paying $15 instead of $25 for that Buzzz because you want the disc but not to put any of "your" money into the pro purse? How is that different than paying a $25 entry and getting $25 worth of merchandise and swag, let alone the "experience"?