Danny was not retired, technically he came when people needed him, he helped or protected them as the case may be. It just turned out that over the years they stopped needing him.
And that was fine, it meant humanity could take care of itself, it meant they were safe. That was what had to matter, no matter that deep down, the halfa was hurt by the information.
It was harder to accept change when you weren't part of it. Danny was immortal, eternal, and powerful, things that no longer fit the world. Not with all the heroes and wizards running around, not with Amity Park fading away, becoming nothing more than a part of his memories.
He fit in perfectly in the Realms, sure, but he knew that if he stayed there too long he'd stop feeling human, and that was dangerous.
So, no, Danny wasn't retired. But he lived in a simple house in Metropolis, though sometimes he got tired of Superman being able to hear literally everything and moved to his house in Fawcett. He used to switch between the two houses frequently, not that it was difficult since he had figured out how to make portals.
He had a few friends, like the orphan boy who lived at the train station and Conner, a teenager who sometimes just needed a house to stay in when he couldn't stand his father.
Neither Conner nor Billy minded his age, which was comforting, although they both got curious when he visited the other house. Danny didn't know how to explain that Eternity Rock and Superman made him nervous if he stayed too long (he didn't like feeling watched), so he just shrugged and told them he had two houses.
Neither of the kids understood but they accepted it. They both had a habit of calling him "Uncle", Danny thought it was odd, given that his appearance wasn't exactly...adult, but it seemed they were comfortable with that, and he left them alone.
Apparently his house (occupied or not) had become a haven for them. Danny always greeted them with a sandwich, or cookies, even though he felt like a grandmother doing so. He smiled for the first time in years, feeling happy to fit into someone's life.
That's why it was quite disconcerting to find the Justice League outside his door asking him to join them. Danny chuckled internally, because the current heroes actually believed they could force him into something, but he accompanied them anyway.
Superboy and Captain Marvel scowled at the League as soon as they entered the Watchtower, when they were told they were bringing in a "dangerous individual" they didn't expect to see their unofficial uncle.