What people are saying is that a 50 mph serve is better than you think it is, in part because you are likely overrating the serves that you do see.
Be careful with the comments about "self proclaimed 4.0s" and "little to no game". You may be the best 3.0 that ever played the game (and that isn't sarcastic, for all I know you are). But there are plenty of experienced 4.0 players on this board that are solid and know what players at various levels can do.
A 4.0 is a player that beats 3.5s and loses to 4.5s - it really is that simple. There are many types of successful skill sets at each of those levels. It might pay to listen a little bit to people that have actually played for years at a level you haven't reached yet. Even if you have more raw skill, you still might learn something.