The quiet fear underneath is that the harshness is what keeps you functioning. That easing off would mean sliding — missed deadlines, effort abandoned, becoming the person you have been outrunning since you were young.
Worth testing rather than assuming.
Look honestly at the periods when you did your best work. Almost nobody, asked straight, names a stretch of maximum self-loathing. The good stretches tend to be the ones where you felt reasonably safe and genuinely interested in something.
Contempt is a stimulant with poor returns. It gets you through a week and costs you a year, and the people who quietly out-produce everyone are rarely the ones at war with themselves.