Capitalist-entrepreneurs must anticipate supply and demand conditions of future market conditions. It is the future price - the appraisement – that must be compared to the costs of factors of production (land, labor, and capital).
There is no going rate of profit. The basic rate is the rate of interest. Profits are the outgrowth of uncertainty. Few accounts about the economy focus on losses. Profits are an index that maladjustments are being met and combatted by the profit-making entrepreneurs. Don’t condemn the profit-making entrepreneur, but the one that has suffered losses. Losses are a sign that he has added further to maladjustment.
The fifth of ten lectures from Joseph Salerno's Introduction to Austrian Economic Analysis seminar.