You can only experience Vampire Survivors for the first time, once, and get that giddy feeling of not knowing what's coming, and oh my gosh aren't there a lot of enemies, and what does this do, and how do I evolve that. Everything is undiscovered and it's the discovery that's a delight.
With repeated play comes the knowledge you'll need to beat it, but also a sense of needing to beat it, and with that comes frustration when you don't - when you don't do as well as the turn before, or build as optimally as you could. And it begins to irk you how long attempts actually take, with all the stopping - much closer to 45 minutes than the 30-minute time-limit levels apparently have. What began as a quick game becomes a slog.
And after a while, though the compulsion is still strong, you find the fun has started to leak out.