(1) in the US, it's changed over the last 2-3 decades as in the past asian girls and asian american girls were more likely to prefer white guys when asians were generally poorer and less assimilated into US society, but US asian guys are steadily getting more attractive to both asians and other girls as they become wealthier and more assimilated
(2) non-asian guys who hear asian girls don't like their own are experiencing a form a survivor bias as the asian girls who want asian guys are less likely to be with those guys to tell them any different.
I grew up in the days of Long Duk Dong and the idea of a white girl dating an asian guy was not even conceivable...asian guys were just not wanted from non-asians and many asians girls alike. Now, I'm constantly taken aback that really hot white, latina, etc other girls are seemingly genuinely into me. In the back of my mind, I still can't quite believe it's real, but times have changed with a lot of wealthy asian guys on wall street, tech, doctors, lawyers, entrepreneurs, etc.