I have been told that don't accept payments via paypal, is that right?
Because when buyer will have his bitcoins then he can claim back money from paypal by saying that i haven't received desired product.
Well in that case, not all people they like bitcoin vice versa with Paypal, Perhaps maybe to other's Paypal was like a nightmare to them vice versa with bitcoin too. Only the difference was in terms of the features of each one Bitcoin is prevailing though I'm not saying Paypal is not good. They are are both helpful but in terms of services bitcoin was still prevailing. This is just my opinion only

I also have a poor past with paypal and hence I hate them, I sold someone my domains and he paid through paypal and after 1 day he just charged back and I lost as paypal asked for bills which I did not had. I since then never used them again and nor will use ever
I of course feel sorry that you got scammed, but that's not PayPal's fault, but fully your responsibility. It's well known that the charge back option gives legit minded people a great feeling of security when buying stuff, but also that this feature gets heavily abused by scammers. It's a hard (not expensive I hope) lesson, but at least you know what to avoid now. Either use Bitcoin, or in case the person you are dealing with doesn't know or use Bitcoin, make use of a payment service that doesn't allow any charge backs.