Paypal is notorious for closing accounts without notice and making it impossible to get your money out short of suing them. The two things that seem to trigger it are receiving an unusually large amount of money on a non-business account or having a large ratio of disputed transactions. "Large ratio" goes by percentage, so if you have 5 transactions and 1 them is disputed that's a 20% dispute rate and will get you shut down.

There's still no true digital version of cash. Bitcoin is close but it's volatility is still too much for most people.