Another cause is the notorious need for approval in this case from colleagues and managers. For many, this is very important (sometimes, way too much). So, if the developers think there is no recognition or impact of their work, they downplay the importance of their participation in the projects which affects their self-esteem, thus, willing to perform.
There are other personal traits that can trigger the burnout which include self-doubt, workaholism, inability to say no, and emotional resistance.