This. Skype has been doing the same for years.

Envato does the same thing; so does Freelancer.

Presumably it costs more to keep the money and process login attempts. Since logging in is enough to keep the account at zero fees, this seems like a money grab.

Is there really a marginal cost to holding more money? Presumably they can buy treasury bonds and earn some interest off the holdings. In terms of data storage, is it really more expensive to store a positive number vs. zero?

> holding and tracking other people's money has a cost.

When you have as many users as PayPal does, in aggregate those non-zero balances are a mountain of money to play with. It's not a cost, it's opportunity for profit.

Holding other peoples money has a profit, not a cost. That float is valuable.

It’s called zero marginal costs for a reason, dude.