Why do Japanese wrestlers have a problem with gajins?

I heard a bit in Chris Jericho's first book how the Japanese wrestlers were notorious for being bastards to foreign wrestlers that came over. I doubt it's the same now considering how many gajins have made their name in Japan like Omega, The Bucks, Karl Anderson and Doc Gallows, even people like Giant Bernard and Will Ospreay, who were already established beforehand, have gotten praise for their work in Japan.

Is it just how the Japanese are as a nation or is the seeming dislike to foreigners because they're mad that the gajins are getting the good matches and taking what they think to be their spot on the card?