The Binding of Isaac: Rebirth

I'm not a fan of Greed mode, and luckily there's a few tactics on how to cheat it. All you need is patience and a whole lot of luck. And patience. But when it works you'll become an unstoppable God, with plenty of money at the end to donate to the machine on each run. Not to mention unlocking some really powerful items for the other modes.

Step One: Get a Blank Card (https://bindingofisaacrebirth.fandom.com/wiki/Blank_Card)
Blank Card is unlocked by beating Isaac with the Eden character. Once it's unlocked in your item pool get ready to start Greed mode, and then get ready to restart that mode dozens of times. You want to enter the first shop, see if Blank Card is buyable, and otherwise restart.
When you finally see the Blank Card (which normally costs 15 coins or 7 if you're lucky) you need the coins for it, so beat the eight normal waves. Buy the card and move on to step two.

Step Two: Get a 2 of Diamonds (https://bindingofisaacrebirth.fandom.com/wiki/Cards_and_Rune...)
If you're super lucky you can find this sometimes in the Curse Room (the room with the spike doors), so always check that room first when you have the Blank Card. Otherwise you need to pray to the shop gods again. Often the shops will sell cards, and since the shops restock automatically in Greed Mode you can buy a card and hope the next one is a Playing Card (see the link for how those cards look like if you're unsure), and then again hope that it's a Diamond and not one of the others. When you finally have both a Blank Card and a 2 of Diamonds you can move on to the final step.

Step Three: Find a shop with Lil' Battery (https://bindingofisaacrebirth.fandom.com/wiki/Batteries#Lil....)
Again, the shops will sometimes sell batteries, which will also automatically restock. So when you finally have all three ingredients you can go nuts. Double your money with Blank Card, buy a new battery when needed, and repeat. And then you can buy all of the (passive) items the shop sells, which it will restock endlessly. You can keep this up until you're bored or scared that the game will crash due to everything happening on screen. But by the end you'll be so powerful that nothing can stop you, and as long as you have 99 coins with a charged Blank Card after beating the final boss you can potentially donate 149 coins to the machine as well.

Some obvious tips
* Greed Mode is no joke, and things can go south very quickly. I've failed plenty of runs with step one and two completed, only to die before I could power myself up by finding a battery. And yes, it's very annoying when it happens. So play carefully.
* Use your character's strengths to your advantage before you're powerful, don't relax until you have everything in place.
* Destroy poop and treasure rocks, explore the curse room (unless you're low on health), anything really to keep you in fighting spirit.
* Some shops will let you reroll the items for the price of a couple of coins. Don't be dumb (like I was plenty of times) and reroll too many times, making you too poor to actually buy the item you want.
* It's better to save your money for 2-3 floors when you're hunting for 2 of Diamonds / battery, rather than rerolling the shop. The next shop might have the item without you spending coins for it.
* If you only have 7 coins or less it's no point in buying the battery, since you won't have enough money to buy the next one after doubling your coins. Move on to the next floor instead in that case.
* You want to avoid buying the following items, which will sabotage this strategy: "Missing No.", "Little Baggy", "Chaos", "Marked" and "? Card".
* Play some other mode in between all of this, to keep you sane.
* And yes, I do prefer this method over actually playing Greed Mode normally.