The rich friend was proud and doubted the end of the world. He should have been grateful to Allah (SWT) for his possessions and said, “That which Allah willed (is in my possession), their is no power expect that of Allah.” After the destruction of his gardens he repented having associated partners with Allah (SWT) i.e. having given the credit of his welfare to his wealth and status and not to Allah (SWT) which too is polytheism. Regarding someone or something other than Allah (SWT) as our benefactor too is polytheism