Should "has" in this sentence be changed into "would have"? [closed]
The sentence is almost fine, as is. Most of the other verbs in the sentence are in the present tense, so why complicate things unnecessarily? I suggest you change blew up to blows up, however, another present-tense verb. So you have:
A hijacker threatens to blow up the plane with himself on it unless he's paid a ransom, but it's a bad strategy because he has too much to lose if the plane really blows up.