The reason capitalism leads to fascism is that inevitably capitalism will lead to untenable inequality. Injustice will be too great to ignore between the rich and the rest. This will lead to populism.
There are two forms of populism. One will seek to rectify the imbalances caused by capitalism. The other will seek to divert blame to minorities. If there were less blacks, immigrants, gays, Jews, etc. etc. then our society would not be in decay. One is much more useful to the Capitalist and so it will ultimately prevail. The capitalist will devote all resources to crushing the leftist populism up to and including directly funding fascism.