You'll lose money all day long with charge backs.
I learned this 10 years ago with mobile phone top up vouchers, had a guy wanted me to email him the code as he needed it ASAP, I sent the code to his paypal email address.
Week later Paypal did a reversal, he claimed his account had been hacked and he never authorized it.
Despite me being able to prove I had emailed it, they still found in his favour.