This is just so false... First off, you're assuming that these 18 y/o kids coming fresh out of high school can play in Europe like it's nothing. You're asking 18 y/o kids, most of whom have never left the country, to live in Europe where they don't speak English and be totally on their own for a year. It's not like their parents can come over like it's nothing, these kids would be totally left to themselves in a foreign, often pretty racist, country totally unable to communicate.
It's also not as good for your draft stock. Yeah scouts "see everything" and all that, but look at the guys and it clearly hurts them. Terrence Ferguson fell totally off of a ton of boards by going to Australia, a much easier transition than other places. Some people thought he'd be a lottery. There's Frank Ntilikina who has always been in Europe, but scouts constantly say how they wish he'd be playing college ball in America and that if he was on a team like Kentucky he'd be way higher. Mudiay was arguably the top prospect coming in, but fell to 7th on draft night. Scouts highly questioned his decision assuming that he may have had some academic issues, and were really disappointed that he didn't play for Larry Brown. His development was clearly stunted by being in China, and he was mismanaged. Brandon Jennings was #1 in high school on ESPN, he fell to 10th come draft time. Another case of stunted development.
People act like these guys can ball out in Europe like it's nothing, leagues like the Spanish league are way tougher than college aside from all the other issues like lack of communication.
Look at the D-League where they make basically nothing. There's a reason they're playing there and not Europe, right?