The fact that a company was successful in the past says nothing about its future success. Many companies have delivered spectacular profits, only to decline later.
This is not strictly true, and it is regrettable that so many keep repeating this demonstrably untrue position. There are many conclusions that can be drawn from past performance. They guarantee nothing, however, they most certainly can be indicators that can help the investor make more informed decisions. Previous success is an indicator that the company at least has the capability to be successful, unlike a company with no track record which may not be capable of success at all and simply be a scam.
"If history teaches us nothing else, it is that we learn nothing from history"