Bolton is trying to reconcile at least two (maybe three) opposing motivations: (1) revenge against Trump, (2) maintenance of a private sector career rooted in a rabidly pro-Israel, anti-Muslim world view (and therefore pro-Trump), and (3) making money on his book.

Which of (1) and (2) will win out remains to be seen. He may decide, selfishly, that (3) can accomplish (1), and that testifying will 'steal the thunder' from (3). Bolton is a consummate egotist. 'Duty' will only come into play if it serves his personal interests, IMO.

My familiarity w/ Bolton dates to the 1970s, when he crossed swords, repeatedly, with my father (then an Ambassador at the UN). He is, IMO, a treacherous, self-promoting, fundamentally disloyal person. Photo L to R: Carl McCall, my father (Richard W. Petree), SoS Muskie, Bolton.