Millions of passengers around the world chose to store their data on airline websites (including those of BA/Aer Lingus) and know nothing about the servers they are stored on. Millions more people use the likes of Amazon, Netflix. All of these airlines and organisations use this "mass data cultivation" in the same way as you suggest Ryanair will do. Fair enough if you feel you can't do that yourself. I assume you don't do online banking either where any breach would be much more costly than the loss of one credit card.
Ryanair offer the use of PayPal as well where no card details are held. I think your own personal dislike of Ryanair (nothing wrong with that if that's how you feel) has clouded your judgement on this occasion.
I have online banking. If the bank wanna lose my details, no probs. Not my fault.
Ryanair on the other hand, you might be told their server was breached sometime the following year.
You're right, I hate them. But I hate them as much as some people love them and their low fares. As I said, great to have a choice.
Without a doubt, some people will blindly upload all their details to these kinds of websites because they know no better. If some people have second thoughts after this, good.