The underlying theme for all commenters on this blog is that we love Michigan and want Michigan to be the best at everything. When something happens that negatively affects that, we will respond differently. Those that respond to this by telling Trey he is making a huge mistake are not "turning on him". They are probably concerned for both him and the Michigan program (maybe not in that order, if you are like me.)
The bottom line is that Trey is making a huge mistake. The only way he is not making a huge mistake is:
1). If he happened to get injured next year.
2). If he, himself feels that he played at his peak this year and has no chance to improve upon this year's performance.
Both of those are unlikely, so he is listening to some bad advice.
In the end this all may be moot, because he could turn out to be great whether he gets drafted or not. But if you are trying to use college to set yourself up for at least one guaranteed contract in the NBA, then this decision makes no sense.