Yes you are very correct Laszlo made history with what he did and as long as bitcoin keeps existing people will always remember him and for me I think this is a big success for him, the world celebrate his action every year.
Some people says Laszlo is regretting his action anywhere he is but that's not true he was interviewed and I watched the interview on YouTube he said his not regretting his action and I believe him because he has made a name that can never die as long as Bitcoin continues to exist and I'm sure that was not only the Bitcoin he was holding he had more Bitcoin and he may still be holding Bitcoin till date, so what exactly will he be regretting, since he has said his not regretting I think we should leave it that way.
Bitcoin is now one of best investment or assets right now in the world and I'm very sure Laszlo is so proud being the first person to make a transaction with it.

He left his impact on the history of BTC and has a whole day to be remembered of what he did - it's a feat of in itself, not to mention that he did to use BTC as it is, not as a stunt or fame (as many do these days).

This is nothing to worry about, because as of then, the value of bitcoin is what we are going to consider and not that of this present time, he should not regret doing that because we don't even know, maybe his action is using bitcoin to buy two pizza boxes was part of the reason that spark for the use and acceptance of bitcoin in making payment more faster as the news spread across the world, thill people begin to consider the use of bitcoin in making any form of payment after the first attempt by Lazlo.

He used it as a currency to pay for what he wants at that time like most of us did in the early stage of Bitcoin.
No one knows that the price of Bitcoin would rise this much, he didn't regret it cause he moved on from it.
I also think that most of those who are active in crypto at that time has already sold their coins when the price increase. drastically from the previous years.

Let us forget about Laszlo Hanyecz that bought 2 pizza for 10K BTC and talk about Papa John who sold the pizza to him because if Papa John is still alive and actually HODL the bitcoins, then he should be tagged along with laszlo as the heros of bitcoin because it would be that Laszlo made bitcoin become popular while Papa John will be so wealthy by now but i doubt if Papa John is still alive because at that time he was already old and this is 15 years after.

Now coming to your question, if i was the one that use 10k BTC to buy 2 pizza then and i now saw how progressive the price have been, i will only regret it if am poor currently but if i'm still rich, there's nothing to regret. Another thing that will make me not to regret much is that i will be happy that am celebrated yearly by bitcoiners because that feeling alone is heavenly.