Why would a guy chat me after 4 years of no contact?

Back in 2020 quarantine I chatted with a guy. We exchanged chats often though almost every day and night. Weird thing, he never asked me for my social media. We only chatted through dating platform and through email. By December same year, I got very few replies until my I no longer got a reply from him. Fast forward 2024 August, he sent me a message through my email. We exchanged short replies until he ghosted again. After 6 days he replied to me said he was busy. I haven't sent him a reply back. Why would he do this? I don't understand.

Why would a guy chat me after 4 years of no contact?
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