The top of the line components aren't always the most durable. For racing, they are often decidedly non-durable. Examples include:

1) Sparsely-spoked wheels.
2) Thin, lightweight tires
3) Cassettes with aluminum cogs (wear out super quickly, but for racing days they save enormous amounts of weight)

Another argument for the rule of thumb of going with the second-best components.

-Cf