He's too cautious.
( He ( ( 's ( too cautious ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBZ 's) (ADJP (RB too) (JJ cautious))) (. .)))
He is cautious due to a lack of confidence.
( He ( ( is ( ( cautious due ) ( to ( ( a lack ) ( of confidence ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBZ is) (ADJP (ADJP (JJ cautious) (JJ due)) (PP (TO to) (NP (NP (DT a) (NN lack)) (PP (IN of) (NP (NN confidence))))))) (. .)))