Well, it used to be easy. You offered the buyer a payment "to family & friends" which did not cost any fees but did not offer any security to the buyer. If you took the money and ran, the seller would have to contact police & co and try to come after you on a private level. BEST for you as the seller.
2nd option was/is the secured payment which costs fees. We all know that. I dont need to teach. ...
I guess the MAIN thing now is that paypal has more and more closed the handcuffs for sellers. Basically, if you offer a "regular" paypal payment with insurance you not only guarantee and secure the buyers money with the help of Paypal-forces BUT you also opened the gates for the buyer to literally claim any bullshit he likes. Even after he already received the goods weeks ago and now all of a sudden he a) needs the money back for some reason you really give a shit about or b) he invents some kind of story, claims sudden damages you didnt know about etc. and maybe even lies about it.
What I dont like about this whole Paypal-thing is literally giving so to say "warranties" and "cash back guarantees" for MONTHS now - on 30+ years old retro parts that I didnt x-ray before selling them. I try to describe everything as accurate as possible. But all we sellers are no magicians! What can we do but upload 20 highly reloluted pictures from all angles and describe the items to the best of our expertise.
Problem is: Paypal is leaning much more towards the buyer here! If he claims any bullshit, paypal rarely decides in your interest as the seller. They prefer happy buyers over happy sellers. Easy as that. And in most of the cases they accept the return of an item - no matter if the explanation is convincing or not and they freeze your (seller´s) money.
Of course, there are plenty of exceptions. And I am very sure, plenty of people will be commenting here how nicely the return claim of their buyer was denied. But IN GENERAL, you open gates and doors for buyers claiming literally any small bullshit to give back the item or to blackmail (partial) refunds from you.
Whenever I can, I try to avoid normal paypal-payments. Everybody is very much invited to come over to my place, have a coffe and check stuff before buying. Everything else is simply wasting my time.
Quick last example:
I sold a nearly perfect XTR M900 crankset with some flaws in the clear coat (of course) but perfect logos - rare. As we all know! I shot 20 high resoluted pics in my ad and described everything very well. The seller bought and blackmailed a return afterwards. I submitted the pics where you could clearly see these marks in the paypal case. It was 4 pictures out of 20 (!). STILL, paypal in a heartbeat froze my money and let the buyer send it back for a full refund. That was enough for me. Paypal to friends only! If not: No need to buy in my shop. Of course I accept normal paypal-payment on a lot of things. But not "per default".