Shìqing fāzhǎn dào zhège dìbù, tā yǐjīng qíhǔ-nánxià le.
With things having gone this far, he's already in too deep to back out.
Tips
memory
Pictured literally: once you're on the tiger's back, jumping off gets you eaten. Stopping is as dangerous as continuing - the exact shape of a sunk-cost / commitment trap.
