A dad watches his son get passed over at a tryout for the third time. He's frustrated, he wants to help, and he has a credit card. Forty-five minutes on Amazon later: a $180 swing sensor, a $90 radar gun, a band set, and a velocity program PDF from an Instagram ad. About $400, sometimes $600 with shipping and a subscription fee.
Three months later, the sensor's in a drawer, the radar gun's been used four times, and the bat speed hasn't moved. Not because the gear doesn't work, but because it got bought in exactly the wrong order.