It's totally natural for a coach to have a moneymaking motive when recommending private training. It's our job as parents to decide if it fits our goals, budget, time, how much their body can handle, etc. In terms of getting better, there're always things to work on. Take striking the ball for example, you can work on driving, chipping, curving with inside and outside of the foot, body positioning, planting foot, the right part of the foot, properly weight of the pass or shot, accuracy, weak foot, doing it at full speed, under pressure, with a defender on your back possibly pushing you, doing it exactly the way you want to after dashing for 20 yards, etc. Extra touches under guidance always help, and your biggest concern as a parent should be over use. I train my kid myself for the most part, but sometimes a different voice is more effective.