Firstly, what mistakes did he make and how did he squander his money? The UNIA was heavily infiltrated by the FBI and some of his closest associates turned out to be FBI agents whose job it was destroy his organization.
Secondly, there's no such thing as a perfect revolution. Whether it was the UNIA, Panthers, Moorish Science Temple, or NOI. Even the Harvest Institute run by Dr. Anderson has problems.
Obviously we should learn from his mistakes of those who came before us, but Garvey's impact far outweighed the errors he made while alive.
On the flip side, it's my personal opinion every black person should be involved in some organization whose goal is for the betterment of the race. You might not be ready/willing to take on a leadership position, but you can still play a part in organizing others.
But like I always state, don't mind me, I'm just another lost nikka