Finally got it…

$a == 1 ? "one" : ( ( $a == 2 ? "two" : $a == 3 ) ? "three" : "other" )

Step 1: Threads starts federating with mastodon

Step 2: mastodon users happily engage with threads, letting it become the biggest fediverse instance

Step 3: threads stops federating with mastodon

Step 4: mastodon users switch over to threads where all conversation is happening, leaving the fediverse deserted

The most outspoken are also the ones generating the most content.