Stripe definitely isn't the only service experiencing this. A legacy system we're in the process of migrating has been hit with a large amount of these in the last month. In particular, they're trying to find the expiration date for the cards - they firehose a hosted payments page with as many card numbers as possible but the same expiration month and year in hopes of hitting the lottery.

We found them to be coming from the same email address. Even when we removed the customer from our system, they'd create a new profile with the same email. To solve the problem in the short term, because they insisted on using the same email every time and were being absolutely relentless - whenever they logged in to a profile with that email, I redirected them to a dummy checkout page. That bought me enough time to write some rules that if someone makes more than X simultaneous connections, it blocks their IP and presents a "please call us" message.

They've tried about a dozen times in the last couple weeks, and they keep shutting themselves down by trying to scale up to a ridiculous number of connections.

The behavior seems strange. They insist on using the same email address and they do nothing to change their approach.