In for a Penny, in for a Pound

What does the idiom “In for a Penny, in for a Pound” mean?

Definition:

Committed to something even though the risks are increasing

For example:

“We knew the project would run into problems sooner or later, but in for a penny, in for a pound.”

Notes:

Also sometimes used in the USA and other places in spite of the fact that the pound is a British unit of currency.