As many have stated here in this thread, P1 is a lot more than just stringing. As they completely customize racquets to the personal specs of each player, they also maintain performance stats, create custom molds for individual players handles and match 60+ racquets a year for each player. Plus pros string every day and change racquets frequently (due to racquet fatigue[getting soft]) to maintain consistency.
Racquets for pro players are tool of the profession; their job. Just like tools a carpenter uses, race car or airline mechanic would use. I dont know of many home car or plane enthusiasts that have a 100k sun analyzer in their garage. Add in the travel and expertise and you see why the charges start at Gold, Silver, and Bronze levels for pro players. If the racquets are taken care of, pros can concentrate on court work outs, physical training, agility/reflex training, gym workouts and dietary measurements aerobic conditioning.
P1 also has services and prices for rec players also that are much more reasonable. So, as a rec you dont need anything like the services the pros require, especially if you are a 3.5 player or lower. However, you would learn and improve faster, if you did have a consistent performance from your tools.