Maybe. People sometimes change their minds about things and it could be this one couple does regret it. I could see a couple who doesn't have a lot going for them getting a little bored in their 50's when going out isn't as fun or they aren't doing as much. Not for all, but I could see for some.
But to be fair, I also have to wonder if maybe a small part of you wishes you didn't have kids, didn't have to make the sacrifices to yourself and your wife. It goes both ways, and this hypothetical could be you projecting your own regrets onto someone else. Who knows?
The number of times I've heard someone who has older kids tell me how they used to travel, be active, have a serious hobby, have a more passionate relationship with their spouse...but then kids came and took over their lives and they had no time for themselves or their romantic life anymore and never really regained it.
Kids can be wonderful and meaningful at times, I have no doubt. But they also compromise your ability to create your own life and affect other important relationships, whether it is your spouse, other family members, or close friends. Independent of when people have kids, the most likely time for divorce is 7 years after the first kid. It puts a big strain on your marriage and your life. Like I said though, for some it is worth it. But for others, there were so many other possibilities to invest in that kids would have rendered impractical.