Yeah you can, but what's more likely, PayPal closing your small account due to many chargebacks in a little time, or them closing a big account with close to average number of chargebacks due to volume?
There will be alternative solutions that exist after Patreon sunsets, simple solutions.
There are alternate solutions that exist now.
The only truly hard part of creating a Patreon clone is getting the approval to accept credit cards, charge them on a recurring basis, and dealing with the red tape around that. Probably the entire rest of the site is comparable to that in complexity. It's not the legendary "replicate in the weekend" project beloved by HN readers, because that whole credit card thing is nontrivial, but it's no "create a new distributed database backend from scratch and pass the Jepsen suite" either.