I usually don't keep my paypal balance up. I typically only have a balance if I sell something to someone (for example on the Marketplace here). Then I use that money to buy something or things and pay for the extra costs with my credit card. But yeah, I have a verified address for shipping and stuff and have only had my credit card linked to the account. The pain in the ass thing is that my wife also has a paypal account (which she has used to sell some things in e-bay, but it's been 5-6 years) and her account is linked to our rewards credit card (we only have two credit cards - one that offers rewards but has higher fees so isn't universally accepted and one that's accepted everywhere). Paypal won't let two accounts be linked to the same credit card, so mine has to be linked to the card that doesn't offer rewards. Things may have changed, but that's how it worked when we both set our our accounts ages ago, so we may have been grandfathered in (I know e-bay does that with some of their policies like my e-bay username used to be the same as part of my e-mail which was allowed in the 90's when I set up my account, but disallowed in the early 00's, but I was allowed to keep my name until a couple years back when I had to do a password reset).

I have occasionally thought about slowly putting a little bit every month into my paypal account to make a slush fund to buy larger things later, but that apparently would require linking it to my bank account so I just save up in the bank account and keep track there instead and keep the interest rather than letting paypal have it. Sure I could make a separate bank account as a "saving for big things like bikes" account but it's not that much work to keep track that I've saved xdollars for other purchases.