I reconsidered the problem, then I found castle drop is too strong when the castle drops near the opponent TC. TC & farms lost is too big to reboom.
CD costs 920 (650 + 270 (with 6 vils forwarding))
5 militaly buildings lost costs 875
1 TC & 8 farms lost costs 855
2 TC lost costs 750
2 TC & 8 farms lost costs 1230
So in this video, he could win this game because first CD did’t eat his economy.
In the T90’s video “The Most Annoying Strategy? The Castle Drop”(can’t post the URL), he couldn’t win because first CD eat his economy directly (and he failed to deal with conqs).
In conclusion, let’s build something within 10 tiles around your TC in order to prevent the opponent from dropping a castle near your eco.