I mean investment sites,the only investment sites that accepts paypal is Forex and PTC,the rest never supports paypal. The alexa rank is far better than that of PM or WMZ,but I want you to see what would happen before middle of next year.
You are right about PTC because Paypal is often used for payment when PTC website doesn't support Payza. However, Paypal is usually second choice after Payza in this kind of business. You are not right about Forex trading. As I see, many broker don't support Paypal because those brokers don't allow US residents. Wire transfer and credit card is more popular than online payment processing in Forex trading.