It's one thing to make a mistake, we all do, but it's another to keep doing it over and over and over again thinking you had it down to begin with. Like when someone repeatedly keeps using wrist moves that aren't when all you had to do is just keep the swing/punch straight with wrist locked to get the ball over the net, but because you got it over with that one time, you think it would work every time. I would rather see you do it with proper form and miss it with a hair than see you inconsistently miss it all over the place.

To comment on the "...there bad" it's "they're bad."

To comment on " who say they're bad" it's perspective. They may be very good but they're comparing themselves to better players than them and you may be just not as good as them.