I had an account that was over 10 years old, but didn't actually have a ton of usage; I didn't have a lot of posts that got upvoted, I think I had under 1000 karma. But I don't regret deleting it at all.
I regret that, ideologically, I don't want to ever reward the leadership there with my patronage in any way, which means there's a ton of content sitting in their archives that I don't want to access now. If I ever had to, I could, but I'd rather do anything else first. Just look what management did; they don't deserve the reward of attention, clicks, or especially additional free content generation, far as I'm concerned.
I guess they were almost right, in a very backwards, stupid way; the main value for me doesn't lie in the users, but in the content. Unfortunately, you can't screw over the users that generate that content in good faith, no matter how much you think you can sell that content for.