It can be argued that economists who give advice to governments and business should have practical experience of economic activities.
As Keynes (1930) remarked “[the economic problem] should be a matter for specialists-like dentistry.” Just as dentists must have successful experience to qualify, so professional economists should have some experience of the economy, not just as consumers but as business people operating in markets.
If they understand money and business, surely they should also be successful, as Keynes was in his stock market operations.
Keynes, J. M. (1930) “Economic Possibilities for our Grandchildren”, in Essays in Persuasion, 358-373. PDF available here.