Don't you understand what is said there?
Of course, everyone wants to sell expensively than the purchase price. It is obvious. But traders and investors do it in different ways. Traders trade risky, short term. Investors use hedged protected positions for the long term. These are various types of earnings.
That is why for investors it is necessary to find projects for long investment that will be working and useful for many years but not for short perion of time.
It does not always have to be long. Any investor will be happy to sell the asset at a profit much earlier than expected.