Yeah but they're punishing you for making your account before you were 18 way later on which is completely unfair
Most services that you use online change their license agreement in order to meet an assortment of expectations, whether they be profit-oriented or legal. I agree that it's unfair but Paypal is literally required to abide by government regulations. Since they are not a government-owned service, they aren't allowed to store currency of minors. They are not banks.
We may amend this Agreement at any time by posting a revised version on our website. The revised version will be effective at the time we post it. If the revised version includes a Substantial Change, we will provide you with 30 Days' prior notice of any Substantial Change by posting a notice on the "Policy Updates" page of our website. All future changes set out in the Policy Update already published on the “Legal Agreements” page of the PayPal website at the time you register for the PayPal Services are incorporated by reference into this Agreement and will take effect as specified in that Policy Update.
it's your money, not theirs.
It's not, this is also in their user agreement. All money you give to paypal becomes their property. The only reason why they give you the money back is because they are regulated by laws and are required to disburse funds that they are given. Regardless, they also reserve the right to shut down accounts for any reason. Seeing as every money-disbursing service requires you to be 18 or older, it is not exclusive to paypal.
Don't get it wrong, Paypal is not a bank. They are a paid service, they abide by a different set of rules. If you put money in the bank, it is still your own money and you have full ownership over it. When you give your money to paypal, it's essentially theirs.