Final answer:
Investors cannot ensure high capital gains just by selecting companies with a history of high profits, as many other factors affect stock prices and market perceptions can change.
Step-by-step explanation:
A financial investor in stocks cannot earn high capital gains simply by buying companies with a demonstrated record of high profits because past performance is not indicative of future results. The price of a stock is driven by both a company's earnings and the market's perception of those earnings, which can be influenced by numerous factors such as economic conditions, market trends, and investor sentiment. Moreover, high profits might already be priced into the stock, making it more challenging to realize significant capital gains.