> The key idea behind this strategy, called Selfish Mining, is for a pool to keep its discovered blocks private, thereby intentionally forking the chain. The honest nodes continue to mine on the public chain, while the pool mines on its own private branch. If the pool discovers more blocks, it develops a longer lead on the public chain, and continues to keep these new blocks private. When the public branch approaches the pool's private branch in length, the selfish miners reveal blocks from their private chain to the public.
> In bitcoin the goal is not to be the first. The goal is to find a winning hash that's on a chain that will not be abandoned.
The goal is to be the first (or very close to the first), because it makes it much more likely that your chain will not be abandoned. If you wait 2 days before you reveal your block, obviously it will be abandoned...