That is, they would make no profit. Again, we can explain profit, on this approach, only if we assume it, by saying that capitalists will not supply goods unless they make a certain rate of profit. Orthodox economics deals with this problem by explaining profit as a composite of 'rewards' for various inputs which the capitalist has in fact supplied. The main capitalist input is supposed to be 'abstinence'. The capitalist with money M could have blown it all on big dinners and expensive treats, but instead invested it for a period, and so deserves a reward.
Profit is the reward for waiting just as wages are the reward for labour.
Ignores the fact that the capitalist investing millions in production has no desire at all to spend his whole fortune in one spree, any more than people in general desire to eat all their week's dinners on Monday. The worker waiting to be paid at the end of the month is the one more likely to be 'abstaining'. Further ignores the fact that the capitalist class as a whole could not consume its whole wealth in one spree, even if they wanted to. Fundamentally, gives no real explanation of economic facts, but only an attempted sentimental apology for them. Other bits added on to the orthodox theory are in the same vein.