meditation on silver-mining

I just learned the slang term "silver-mining" from an L.A. Times piece about people who live in tunnels under Las Vegas:

...they made their way into the blinding sun and hustled for dope and food -- usually, by "silver-mining." They hovered at casinos, hoping slot players left them credits to play or winnings to cash.

A variant term is "slot-walking."

I've silver-mined, sure

Taken from others' bounty

And walked on

Or left some currency to spare

For others on a dare

Walking the slot

The narrow verge

Between this and that

The infinite space between jackpot and bust

Faith and trust

Diamond and rust

Silver-mining

Some call it

Gambling others scavenging

What about grace

Left dangling

Like a participle

Waiting?