It's funny to see the same old thread several times a week...
It's been said before: paypal has a nasty feature, allowing you to chargeback any payment for over 180 days.
This is why it'll be nearly impossible for you to find anybody willing to trade PP to BTC, as long as you don't have enough trust...
You can always use virwox to exchange PP to BTC. They charge a very big fee, and it can take up to 2 days to withdraw the money, but it's basically our only alternative.
You said all correct, even if not every user is a scammer but you can not trust anymore.
Use virwox and you are safe for 100$ you pay around 10$ fees