Hi, I had the same problem and made a workaround for this.
Edit your vi /etc/rc.local.d/local.sh
that it looks like this:
/bin/kill $(cat /var/run/crond.pid)
/bin/echo "* 1 * * * /opt/ghettovcb/bin/ghettoVCB.sh -a > /vmfs/volumes/Slot_4/ghettoVCB/ghettoVCB-backup-\$(date +\\%F-\\%H-\\%M-\\%S).log" >> /var/spool/cron/crontabs
/bin/cp /vmfs/volumes/Slot_4/ghettoVCB/ghettoVCB.sh /opt/ghettovcb/bin/ghettoVCB.sh
after booting up the esxi will copy the files from (in my case) location where you store the cript and/or config and so you overwrite the overwritten