I have to assume that 90% of the kids and their families don't think that way and I think that may be a low percentage. They don't understand that you'll rarely make over $100,000 as a rookie in Europe. They don't understand that the NBA isn't just a talent league but a "fit" league. There are many players who are talented enough to make the NBA but never make it because of certain issues.
Contracts in Europe are rarely over a year (with a few exceptions) or guaranteed. If they don't produce in Europe they'll be released. They need their "imports" to produce or they'll find another one. It's very cutthroat over there. Most guys think they'll make a ton of money, playing in front of a ton of people, and then come back to the NBA. Money isn't as big as they think, attendance isn't as big unless you are on a premier club (many gyms are the size of HS gyms), and can't make in the NBA if your agent doesn't have the contacts.