If there are "so many dangerous terrorists" worthy of trillions of dollars of military spending to protect me (I'm in the US, but all governments invoke terrori

If there are "so many dangerous terrorists" worthy of trillions of dollars of military spending to protect me (I'm in the US, but all governments invoke terrorism as justification), why aren't those terrorists utilizing viral weapons like this person describes? Is there something that could stop this kind of threat, if it is as real as described?