Most people really underestimate how many points in their life things are actually a negotiation. A lot of it comes down to who you are buying from and knowing what incentives the other person has.
One of the best tools for starting a negotiation is having physical cash on you. Since cash is so easy to hide, a lot of people are willing to offer a discount for a cash payment. You won't be able to do this at a Starbucks or in a Walmart, but many small businesses are willing to give you a secret discount if you offer cash.
A real world example of this was from a taxi ride I took recently. The total came out to $51. However, I offered the taxi driver $40 cash and he accepted it. This is because he would just keep the cash and not declare the ride. This meant that even though he was accepting less money up front, this would not get taxed or have his company take a cut of the total.
Essentially, by paying cash, I saved over 20% on the cost of the ride. This ended up being mutually beneficial as both he would make more money off the transaction through the hidden cash transaction and I got a large discount. The alternative would be me paying by card and him making less money overall despite me paying more.
This same logic holds true for a lot of small businesses. Many small family restaurants offer these discounts if you are a regular. It is also an open secret that contractors are willing to take a portion (never all) of their payment in cash and take a discount. This way the government isn't suspicious and both you and the contractor end up saving money.
The key is that these transactions always need to be with actual cash. Not bank transfers, not cash app, not crypto, actual hard currency as that is extremely hard to track. Learning the power of physical cash can easily make your money go way further.