The stats on that are outdated and from a tiny sample where a significant number dropped out.

That said, I'd guess that most do not have regret. But as someone who likes the scientific method - I know that is not good enough. We need real data points

What we do know, is that the statistics on de-transitioners is pretty horrible. They feel terrible shame - and tend not to be seen. And the non-de-transitioners (those happy)? Well, they also drop out of the stats because they go on with their lives. Why would they want to keep in touch if everything is going well.

(So, we suck at data collection in both ways).

Over the next few years, I think we'll find out.