Buying a Gibson Les Paul Custom isn't going to make you a great guitarist right away, however, it's going to help you get there a lot quicker. That's been my experience in every hobby I've ever had.
Mountain biking, photography, guitars, BMX, hillwalking, running. Buy the best you can afford and it'll make it a lot more enjoyable, and you'll likely progress quicker.
Coupled with a desire to learn very fast from your mistakes and there's no stopping you.