Learn English – Idiom for being forced to dig your own grave

You might want a to use an actual, well-known economics term:

• R.O.I: "Return On Investment"

Or

• "Pays for itself"

You would then explain how the subject does this.

Or you might want

• "you can't make an omlette without breaking a few eggs"

suggesting that a price MUST be paid to get the intended benefit.

or

• "Killer app", short for "killer application"

which refers to the fact that the very first spreadsheet program for a personal computer allowed accountants|book keepers to justify the entire cost of purchasing an entire expensive PC system because it would divide their workload by a factor of 10 or more. If the computer ONLY ran a spreadsheet, it was worth the price to them. But a computer also does much, much more, like print layout for documents, art, e-Mail, etc..

You might want:

• "Get the ball rolling"

Which conjures the image of giving a boulder a tiny initial push to start it rolling down a hill, after which gravity will take over & keep it rolling.

Consider mortify if you can tolerate a colourful word rather than an idiom.

Definition from O-D

1. Cause (someone) to feel very embarrassed or ashamed [...]

Its etymology is slightly reminiscent of the grave / death reference mentioned by OP, i.e.

Late Middle English (in the senses 'put to death', 'deaden', and 'subdue by self-denial'): from Old French mortifier, from ecclesiastical Latin mortificare 'kill, subdue', from mors,mort- 'death'.

To quote a UK MP in news today:

Mr Duncan Smith told Robert Peston on his ITV politics show: 

“I’ve been around in politics long enough to see plenty of incredibly experienced cabinet ministers and Prime Ministers get stitched up in the course of an interview.

“I’ve talked to her, she’s actually mortified about that, really genuinely mortified. - Independent Newspaper