be cutting (one's) own throat

To be causing problems for oneself with one's own actions (which are often motivated by anger). I know you're mad at me, but I really think you're cutting your own throat here—running away is only going to make your life harder. Tom accounts for nearly 75% of his branch's quarterly sales. So, as much as he annoys you, you'd be cutting your own throat to fire him, sir. Look, you're cutting your own throat when you react so defensively. It makes the media think you have something to hide.

be cutting your own throat

If someone is cutting their own throat, they are doing something which will damage them or make them fail. I think the union is cutting its own throat because if they go on strike, there will be even more jobs lost. Note: The verb slit is sometimes used instead of cut. They are slitting their own throats by putting their prices up.