An intro would be also be kind of mainstream, but I'll still be...
Cutting to the chase
Rotations and balancing are kind of boring, but invariants are not. The nice thing about in looking for different solutions for the same problem is that you can find elegance in each of them. Maybe more importantly, it helps you develop backups when the first solution fails.
It is just the fact that sometimes to sell and start over is the right call. Of course, starting off with a small amount of one million dollars would do(couldn't help myself, people keep saying orange is the new black(now seriously: I say Donald, you say... Knuth))
