How secure is Paypal ?

I would suggest that you do the other way, transfer your paypal balance or your sales (example buyer paid you using paypal) to your bank account. To avoid this kind of dispute always make sure to indicate the tracking numbers or even keep a copy of it for your records. So just in case the buyer open a claim that item is not received you have an evidence that the item has been shipped and delivered. I think PayPal will not just deduct automatically from your account, once a dispute for "item is not received" has been open, both buyer and seller will be given the opportunity to respond and present their case. I hope this helps.