Imagine you have wallets with different amounts of cash in them.

If you spend more than what's in one of those wallets, you have to go get another one.. That takes time and energy.

Money is a representation of your time and energy so in a way, whatever you're buying now costs more-time, energy, and money.

Utxos are like wallets. They're just all kept in the same place. It's a specific amount of money or value in one place at a time.

What we call Bitcoin wallets are more like files that have all those wallets in one place.

Spend more than what's in one, it costs more to spend from another.